Edit

Share via

ASP.NET Core breaking changes for versions 3.0 and 3.1

  • Article

ASP.NET Core provides the web app development features used by .NET Core.

Select one of the following links for breaking changes in a specific version:

The following breaking changes in ASP.NET Core 3.0 and 3.1 are documented on this page:

ASP.NET Core 3.1

HTTP: Browser SameSite changes impact authentication

Some browsers, such as Chrome and Firefox, made breaking changes to their implementations of SameSite for cookies. The changes impact remote authentication scenarios, such as OpenID Connect and WS-Federation, which must opt out by sending SameSite=None. However, SameSite=None breaks on iOS 12 and some older versions of other browsers. The app needs to sniff these versions and omit SameSite.

For discussion on this issue, see dotnet/aspnetcore#14996.

Version introduced

3.1 Preview 1

Old behavior

SameSite is a 2016 draft standard extension to HTTP cookies. It's intended to mitigate Cross-Site Request Forgery (CSRF). This was originally designed as a feature the servers would opt into by adding the new parameters. ASP.NET Core 2.0 added initial support for SameSite.

New behavior

Google proposed a new draft standard that isn't backwards compatible. The standard changes the default mode to Lax and adds a new entry None to opt out. Lax suffices for most app cookies; however, it breaks cross-site scenarios like OpenID Connect and WS-Federation login. Most OAuth logins aren't affected because of differences in how the request flows. The new None parameter causes compatibility problems with clients that implemented the prior draft standard (for example, iOS 12). Chrome 80 will include the changes. See SameSite Updates for the Chrome product launch timeline.

ASP.NET Core 3.1 has been updated to implement the new SameSite behavior. The update redefines the behavior of SameSiteMode.None to emit SameSite=None and adds a new value SameSiteMode.Unspecified to omit the SameSite attribute. All cookie APIs now default to Unspecified, though some components that use cookies set values more specific to their scenarios such as the OpenID Connect correlation and nonce cookies.

For other recent changes in this area, see HTTP: Some cookie SameSite defaults changed to None. In ASP.NET Core 3.0, most defaults were changed from SameSiteMode.Lax to SameSiteMode.None (but still using the prior standard).

Reason for change

Browser and specification changes as outlined in the preceding text.

Apps that interact with remote sites, such as through third-party login, need to:

  • Test those scenarios on multiple browsers.
  • Apply the cookie policy browser sniffing mitigation discussed in Support older browsers.

For testing and browser sniffing instructions, see the following section.

Determine if you're affected

Test your web app using a client version that can opt into the new behavior. Chrome, Firefox, and Microsoft Edge Chromium all have new opt-in feature flags that can be used for testing. Verify that your app is compatible with older client versions after you've applied the patches, especially Safari. For more information, see Support older browsers.

Chrome

Chrome 78 and later yield misleading test results. Those versions have a temporary mitigation in place and allow cookies less than two minutes old. With the appropriate test flags enabled, Chrome 76 and 77 yield more accurate results. To test the new behavior, toggle chrome://flags/#same-site-by-default-cookies to enabled. Chrome 75 and earlier are reported to fail with the new None setting. For more information, see Support older browsers.

Google doesn't make older Chrome versions available. You can, however, download older versions of Chromium, which will suffice for testing. Follow the instructions at Download Chromium.

Safari

Safari 12 strictly implemented the prior draft and fails if it sees the new None value in cookies. This must be avoided via the browser sniffing code shown in Support older browsers. Ensure you test Safari 12 and 13 as well as WebKit-based, OS-style logins using Microsoft Authentication Library (MSAL), Active Directory Authentication Library (ADAL), or whichever library you're using. The problem is dependent on the underlying OS version. OSX Mojave 10.14 and iOS 12 are known to have compatibility problems with the new behavior. Upgrading to OSX Catalina 10.15 or iOS 13 fixes the problem. Safari doesn't currently have an opt-in flag for testing the new specification behavior.

Firefox

Firefox support for the new standard can be tested on version 68 and later by opting in on the about:config page with the feature flag network.cookie.sameSite.laxByDefault. No compatibility issues have been reported on older versions of Firefox.

Microsoft Edge

While Microsoft Edge supports the old SameSite standard, as of version 44 it didn't have any compatibility problems with the new standard.

Microsoft Edge Chromium

The feature flag is edge://flags/#same-site-by-default-cookies. No compatibility issues were observed when testing with Microsoft Edge Chromium 78.

Electron

Versions of Electron include older versions of Chromium. For example, the version of Electron used by Microsoft Teams is Chromium 66, which exhibits the older behavior. Perform your own compatibility testing with the version of Electron your product uses. For more information, see Support older browsers.

Support older browsers

The 2016 SameSite standard mandated that unknown values be treated as SameSite=Strict values. Consequently, any older browsers that support the original standard may break when they see a SameSite property with a value of None. Web apps must implement browser sniffing if they intend to support these old browsers. ASP.NET Core doesn't implement browser sniffing for you because User-Agent request header values are highly unstable and change on a weekly basis. Instead, an extension point in the cookie policy allows you to add User-Agent-specific logic.

In Startup.cs, add the following code:

private void CheckSameSite(HttpContext httpContext, CookieOptions options)
{
    if (options.SameSite == SameSiteMode.None)
    {
        var userAgent = httpContext.Request.Headers["User-Agent"].ToString();
        // TODO: Use your User Agent library of choice here.
        if (/* UserAgent doesn't support new behavior */)
        {
            options.SameSite = SameSiteMode.Unspecified;
        }
    }
}

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<CookiePolicyOptions>(options =>
    {
        options.MinimumSameSitePolicy = SameSiteMode.Unspecified;
        options.OnAppendCookie = cookieContext =>
            CheckSameSite(cookieContext.Context, cookieContext.CookieOptions);
        options.OnDeleteCookie = cookieContext =>
            CheckSameSite(cookieContext.Context, cookieContext.CookieOptions);
    });
}

public void Configure(IApplicationBuilder app)
{
    // Before UseAuthentication or anything else that writes cookies.
    app.UseCookiePolicy();

    app.UseAuthentication();
    // code omitted for brevity
}
Opt-out switches

The Microsoft.AspNetCore.SuppressSameSiteNone compatibility switch enables you to temporarily opt out of the new ASP.NET Core cookie behavior. Add the following JSON to a runtimeconfig.template.json file in your project:

{
  "configProperties": {
    "Microsoft.AspNetCore.SuppressSameSiteNone": "true"
  }
}
Other Versions

Related SameSite patches are forthcoming for:

  • ASP.NET Core 2.1, 2.2, and 3.0
  • Microsoft.Owin 4.1
  • System.Web (for .NET Framework 4.7.2 and later)

Category

ASP.NET

Affected APIs

ASP.NET Core 3.0

Obsolete Antiforgery, CORS, Diagnostics, MVC, and Routing APIs removed

Obsolete members and compatibility switches in ASP.NET Core 2.2 were removed.

Version introduced

3.0

Reason for change

Improvement of API surface over time.

While targeting .NET Core 2.2, follow the guidance in the obsolete build messages to adopt new APIs instead.

Category

ASP.NET Core

Affected APIs

The following types and members were marked as obsolete for ASP.NET Core 2.1 and 2.2:

Types

  • Microsoft.AspNetCore.Diagnostics.Views.WelcomePage
  • Microsoft.AspNetCore.DiagnosticsViewPage.Views.AttributeValue
  • Microsoft.AspNetCore.DiagnosticsViewPage.Views.BaseView
  • Microsoft.AspNetCore.DiagnosticsViewPage.Views.HelperResult
  • Microsoft.AspNetCore.Mvc.Formatters.Xml.ProblemDetails21Wrapper
  • Microsoft.AspNetCore.Mvc.Formatters.Xml.ValidationProblemDetails21Wrapper
  • Microsoft.AspNetCore.Mvc.Razor.Compilation.ViewsFeatureProvider
  • Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageArgumentBinder
  • Microsoft.AspNetCore.Routing.IRouteValuesAddressMetadata
  • Microsoft.AspNetCore.Routing.RouteValuesAddressMetadata

Constructors

  • Microsoft.AspNetCore.Cors.Infrastructure.CorsService(IOptions{CorsOptions})
  • Microsoft.AspNetCore.Routing.Tree.TreeRouteBuilder(ILoggerFactory,UrlEncoder,ObjectPool{UriBuildingContext},IInlineConstraintResolver)
  • Microsoft.AspNetCore.Mvc.Formatters.OutputFormatterCanWriteContext
  • Microsoft.AspNetCore.Mvc.ApiExplorer.DefaultApiDescriptionProvider(IOptions{MvcOptions},IInlineConstraintResolver,IModelMetadataProvider)
  • Microsoft.AspNetCore.Mvc.ApiExplorer.DefaultApiDescriptionProvider(IOptions{MvcOptions},IInlineConstraintResolver,IModelMetadataProvider,IActionResultTypeMapper)
  • Microsoft.AspNetCore.Mvc.Formatters.FormatFilter(IOptions{MvcOptions})
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ArrayModelBinder`1(IModelBinder)
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ByteArrayModelBinder
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.CollectionModelBinder`1(IModelBinder)
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.ComplexTypeModelBinder(IDictionary`2)
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.DictionaryModelBinder`2(IModelBinder,IModelBinder)
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.DoubleModelBinder(System.Globalization.NumberStyles)
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.FloatModelBinder(System.Globalization.NumberStyles)
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.FormCollectionModelBinder
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.FormFileModelBinder
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.HeaderModelBinder
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.KeyValuePairModelBinder`2(IModelBinder,IModelBinder)
  • Microsoft.AspNetCore.Mvc.ModelBinding.Binders.SimpleTypeModelBinder(System.Type)
  • Microsoft.AspNetCore.Mvc.ModelBinding.ModelAttributes(IEnumerable{System.Object})
  • Microsoft.AspNetCore.Mvc.ModelBinding.ModelAttributes(IEnumerable{System.Object},IEnumerable{System.Object})
  • Microsoft.AspNetCore.Mvc.ModelBinding.ModelBinderFactory(IModelMetadataProvider,IOptions{MvcOptions})
  • Microsoft.AspNetCore.Mvc.ModelBinding.ParameterBinder(IModelMetadataProvider,IModelBinderFactory,IObjectModelValidator)
  • Microsoft.AspNetCore.Mvc.Routing.KnownRouteValueConstraint()
  • Microsoft.AspNetCore.Mvc.Formatters.XmlDataContractSerializerInputFormatter
  • Microsoft.AspNetCore.Mvc.Formatters.XmlDataContractSerializerInputFormatter(System.Boolean)
  • Microsoft.AspNetCore.Mvc.Formatters.XmlDataContractSerializerInputFormatter(MvcOptions)
  • Microsoft.AspNetCore.Mvc.Formatters.XmlSerializerInputFormatter
  • Microsoft.AspNetCore.Mvc.Formatters.XmlSerializerInputFormatter(System.Boolean)
  • Microsoft.AspNetCore.Mvc.Formatters.XmlSerializerInputFormatter(MvcOptions)
  • Microsoft.AspNetCore.Mvc.TagHelpers.ImageTagHelper(IHostingEnvironment,IMemoryCache,HtmlEncoder,IUrlHelperFactory)
  • Microsoft.AspNetCore.Mvc.TagHelpers.LinkTagHelper(IHostingEnvironment,IMemoryCache,HtmlEncoder,JavaScriptEncoder,IUrlHelperFactory)
  • Microsoft.AspNetCore.Mvc.TagHelpers.ScriptTagHelper(IHostingEnvironment,IMemoryCache,HtmlEncoder,JavaScriptEncoder,IUrlHelperFactory)
  • Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.RazorPageAdapter(RazorPageBase)

Properties

  • Microsoft.AspNetCore.Antiforgery.AntiforgeryOptions.CookieDomain
  • Microsoft.AspNetCore.Antiforgery.AntiforgeryOptions.CookieName
  • Microsoft.AspNetCore.Antiforgery.AntiforgeryOptions.CookiePath
  • Microsoft.AspNetCore.Antiforgery.AntiforgeryOptions.RequireSsl
  • Microsoft.AspNetCore.Mvc.ApiBehaviorOptions.AllowInferringBindingSourceForCollectionTypesAsFromQuery
  • Microsoft.AspNetCore.Mvc.ApiBehaviorOptions.SuppressUseValidationProblemDetailsForInvalidModelStateResponses
  • Microsoft.AspNetCore.Mvc.CookieTempDataProviderOptions.CookieName
  • Microsoft.AspNetCore.Mvc.CookieTempDataProviderOptions.Domain
  • Microsoft.AspNetCore.Mvc.CookieTempDataProviderOptions.Path
  • Microsoft.AspNetCore.Mvc.DataAnnotations.MvcDataAnnotationsLocalizationOptions.AllowDataAnnotationsLocalizationForEnumDisplayAttributes
  • Microsoft.AspNetCore.Mvc.Formatters.Xml.MvcXmlOptions.AllowRfc7807CompliantProblemDetailsFormat
  • Microsoft.AspNetCore.Mvc.MvcOptions.AllowBindingHeaderValuesToNonStringModelTypes
  • Microsoft.AspNetCore.Mvc.MvcOptions.AllowCombiningAuthorizeFilters
  • Microsoft.AspNetCore.Mvc.MvcOptions.AllowShortCircuitingValidationWhenNoValidatorsArePresent
  • Microsoft.AspNetCore.Mvc.MvcOptions.AllowValidatingTopLevelNodes
  • Microsoft.AspNetCore.Mvc.MvcOptions.InputFormatterExceptionPolicy
  • Microsoft.AspNetCore.Mvc.MvcOptions.SuppressBindingUndefinedValueToEnumType
  • Microsoft.AspNetCore.Mvc.MvcViewOptions.AllowRenderingMaxLengthAttribute
  • Microsoft.AspNetCore.Mvc.MvcViewOptions.SuppressTempDataAttributePrefix
  • Microsoft.AspNetCore.Mvc.RazorPages.RazorPagesOptions.AllowAreas
  • Microsoft.AspNetCore.Mvc.RazorPages.RazorPagesOptions.AllowDefaultHandlingForOptionsRequests
  • Microsoft.AspNetCore.Mvc.RazorPages.RazorPagesOptions.AllowMappingHeadRequestsToGetHandler

Methods

Authentication: Google+ deprecated and replaced

Google is starting to shut down Google+ Sign-in for apps as early as January 28, 2019.

Change description

ASP.NET 4.x and ASP.NET Core have been using the Google+ Sign-in APIs to authenticate Google account users in web apps. The affected NuGet packages are Microsoft.AspNetCore.Authentication.Google for ASP.NET Core and Microsoft.Owin.Security.Google for Microsoft.Owin with ASP.NET Web Forms and MVC.

Google's replacement APIs use a different data source and format. The mitigations and solutions provided below account for the structural changes. Apps should verify the data itself still satisfies their requirements. For example, names, email addresses, profile links, and profile photos may provide subtly different values than before.

Version introduced

All versions. This change is external to ASP.NET Core.

Owin with ASP.NET Web Forms and MVC

For Microsoft.Owin 3.1.0 and later, a temporary mitigation is outlined here. Apps should complete testing with the mitigation to check for changes in the data format. There are plans to release Microsoft.Owin 4.0.1 with a fix. Apps using any prior version should update to version 4.0.1.

ASP.NET Core 1.x

The mitigation in Owin with ASP.NET Web Forms and MVC can be adapted to ASP.NET Core 1.x. NuGet package patches aren't planned because 1.x has reached end of life status.

ASP.NET Core 2.x

For Microsoft.AspNetCore.Authentication.Google version 2.x, replace your existing call to AddGoogle in Startup.ConfigureServices with the following code:

.AddGoogle(o =>
{
    o.ClientId = Configuration["Authentication:Google:ClientId"];
    o.ClientSecret = Configuration["Authentication:Google:ClientSecret"];
    o.UserInformationEndpoint = "https://www.googleapis.com/oauth2/v2/userinfo";
    o.ClaimActions.Clear();
    o.ClaimActions.MapJsonKey(ClaimTypes.NameIdentifier, "id");
    o.ClaimActions.MapJsonKey(ClaimTypes.Name, "name");
    o.ClaimActions.MapJsonKey(ClaimTypes.GivenName, "given_name");
    o.ClaimActions.MapJsonKey(ClaimTypes.Surname, "family_name");
    o.ClaimActions.MapJsonKey("urn:google:profile", "link");
    o.ClaimActions.MapJsonKey(ClaimTypes.Email, "email");
});

The February 2.1 and 2.2 patches incorporated the preceding reconfiguration as the new default. No patch is planned for ASP.NET Core 2.0 since it has reached end of life.

ASP.NET Core 3.0

The mitigation given for ASP.NET Core 2.x can also be used for ASP.NET Core 3.0. In future 3.0 previews, the Microsoft.AspNetCore.Authentication.Google package may be removed. Users would be directed to Microsoft.AspNetCore.Authentication.OpenIdConnect instead. The following code shows how to replace AddGoogle with AddOpenIdConnect in Startup.ConfigureServices. This replacement can be used with ASP.NET Core 2.0 and later and can be adapted for ASP.NET Core 1.x as needed.

.AddOpenIdConnect("Google", o =>
{
    o.ClientId = Configuration["Authentication:Google:ClientId"];
    o.ClientSecret = Configuration["Authentication:Google:ClientSecret"];
    o.Authority = "https://accounts.google.com";
    o.ResponseType = OpenIdConnectResponseType.Code;
    o.CallbackPath = "/signin-google"; // Or register the default "/signin-oidc"
    o.Scope.Add("email");
});
JwtSecurityTokenHandler.DefaultInboundClaimTypeMap.Clear();

Category

ASP.NET Core

Affected APIs

Microsoft.AspNetCore.Authentication.Google

Authentication: HttpContext.Authentication property removed

The deprecated Authentication property on HttpContext has been removed.

Change description

As part of dotnet/aspnetcore#6504, the deprecated Authentication property on HttpContext has been removed. The Authentication property has been deprecated since 2.0. A migration guide was published to migrate code using this deprecated property to the new replacement APIs. The remaining unused classes / APIs related to the old ASP.NET Core 1.x authentication stack were removed in commit dotnet/aspnetcore@d7a7c65.

For discussion, see dotnet/aspnetcore#6533.

Version introduced

3.0

Reason for change

ASP.NET Core 1.0 APIs have been replaced by extension methods in Microsoft.AspNetCore.Authentication.AuthenticationHttpContextExtensions.

See the migration guide.

Category

ASP.NET Core

Affected APIs

Authentication: Newtonsoft.Json types replaced

In ASP.NET Core 3.0, Newtonsoft.Json types used in Authentication APIs have been replaced with System.Text.Json types. Except for the following cases, basic usage of the Authentication packages remains unaffected:

  • Classes derived from the OAuth providers, such as those from aspnet-contrib.
  • Advanced claim manipulation implementations.

For more information, see dotnet/aspnetcore#7105. For discussion, see dotnet/aspnetcore#7289.

Version introduced

3.0

For derived OAuth implementations, the most common change is to replace JObject.Parse with JsonDocument.Parse in the CreateTicketAsync override as shown here. JsonDocument implements IDisposable.

The following list outlines known changes:

Category

ASP.NET Core

Affected APIs

Authentication: OAuthHandler ExchangeCodeAsync signature changed

In ASP.NET Core 3.0, the signature of OAuthHandler.ExchangeCodeAsync was changed from:

protected virtual System.Threading.Tasks.Task<Microsoft.AspNetCore.Authentication.OAuth.OAuthTokenResponse> ExchangeCodeAsync(string code, string redirectUri) { throw null; }

To:

protected virtual System.Threading.Tasks.Task<Microsoft.AspNetCore.Authentication.OAuth.OAuthTokenResponse> ExchangeCodeAsync(Microsoft.AspNetCore.Authentication.OAuth.OAuthCodeExchangeContext context) { throw null; }

Version introduced

3.0

Old behavior

The code and redirectUri strings were passed as separate arguments.

New behavior

Code and RedirectUri are properties on OAuthCodeExchangeContext that can be set via the OAuthCodeExchangeContext constructor. The new OAuthCodeExchangeContext type is the only argument passed to OAuthHandler.ExchangeCodeAsync.

Reason for change

This change allows additional parameters to be provided in a non-breaking manner. There's no need to create new ExchangeCodeAsync overloads.

Construct an OAuthCodeExchangeContext with the appropriate code and redirectUri values. An AuthenticationProperties instance must be provided. This single OAuthCodeExchangeContext instance can be passed to OAuthHandler.ExchangeCodeAsync instead of multiple arguments.

Category

ASP.NET Core

Affected APIs

OAuthHandler<TOptions>.ExchangeCodeAsync(String, String)

Authorization: AddAuthorization overload moved to different assembly

The core AddAuthorization methods that used to reside in Microsoft.AspNetCore.Authorization were renamed to AddAuthorizationCore. The old AddAuthorization methods still exist, but are in the Microsoft.AspNetCore.Authorization.Policy assembly instead. Apps using both methods should see no impact. Note that Microsoft.AspNetCore.Authorization.Policy now ships in the shared framework rather than a standalone package as discussed in Shared framework: Assemblies removed from Microsoft.AspNetCore.App.

Version introduced

3.0

Old behavior

AddAuthorization methods existed in Microsoft.AspNetCore.Authorization.

New behavior

AddAuthorization methods exist in Microsoft.AspNetCore.Authorization.Policy. AddAuthorizationCore is the new name for the old methods.

Reason for change

AddAuthorization is a better method name for adding all common services needed for authorization.

Either add a reference to Microsoft.AspNetCore.Authorization.Policy or use AddAuthorizationCore instead.

Category

ASP.NET Core

Affected APIs

Microsoft.Extensions.DependencyInjection.AuthorizationServiceCollectionExtensions.AddAuthorization(IServiceCollection, Action<AuthorizationOptions>)

Authorization: IAllowAnonymous removed from AuthorizationFilterContext.Filters

As of ASP.NET Core 3.0, MVC doesn't add AllowAnonymousFilters for [AllowAnonymous] attributes that were discovered on controllers and action methods. This change is addressed locally for derivatives of AuthorizeAttribute, but it's a breaking change for IAsyncAuthorizationFilter and IAuthorizationFilter implementations. Such implementations wrapped in a [TypeFilter] attribute are a popular and supported way to achieve strongly-typed, attribute-based authorization when both configuration and dependency injection are required.

Version introduced

3.0

Old behavior

IAllowAnonymous appeared in the AuthorizationFilterContext.Filters collection. Testing for the interface's presence was a valid approach to override or disable the filter on individual controller methods.

New behavior

IAllowAnonymous no longer appears in the AuthorizationFilterContext.Filters collection. IAsyncAuthorizationFilter implementations that are dependent on the old behavior typically cause intermittent HTTP 401 Unauthorized or HTTP 403 Forbidden responses.

Reason for change

A new endpoint routing strategy was introduced in ASP.NET Core 3.0.

Search the endpoint metadata for IAllowAnonymous. For example:

var endpoint = context.HttpContext.GetEndpoint();
if (endpoint?.Metadata?.GetMetadata<IAllowAnonymous>() != null)
{
}

An example of this technique is seen in this HasAllowAnonymous method.

Category

ASP.NET Core

Affected APIs

None

Authorization: IAuthorizationPolicyProvider implementations require new method

In ASP.NET Core 3.0, a new GetFallbackPolicyAsync method was added to IAuthorizationPolicyProvider. This fallback policy is used by the authorization middleware when no policy is specified.

For more information, see dotnet/aspnetcore#9759.

Version introduced

3.0

Old behavior

Implementations of IAuthorizationPolicyProvider didn't require a GetFallbackPolicyAsync method.

New behavior

Implementations of IAuthorizationPolicyProvider require a GetFallbackPolicyAsync method.

Reason for change

A new method was needed for the new AuthorizationMiddleware to use when no policy is specified.

Add the GetFallbackPolicyAsync method to your implementations of IAuthorizationPolicyProvider.

Category

ASP.NET Core

Affected APIs

Microsoft.AspNetCore.Authorization.IAuthorizationPolicyProvider

Caching: CompactOnMemoryPressure property removed

The ASP.NET Core 3.0 release removed the obsolete MemoryCacheOptions APIs.

Change description

This change is a follow-up to aspnet/Caching#221. For discussion, see dotnet/extensions#1062.

Version introduced

3.0

Old behavior

MemoryCacheOptions.CompactOnMemoryPressure property was available.

New behavior

The MemoryCacheOptions.CompactOnMemoryPressure property has been removed.

Reason for change

Automatically compacting the cache caused problems. To avoid unexpected behavior, the cache should only be compacted when needed.

To compact the cache, downcast to MemoryCache and call Compact when needed.

Category

ASP.NET Core

Affected APIs

MemoryCacheOptions.CompactOnMemoryPressure

Caching: Microsoft.Extensions.Caching.SqlServer uses new SqlClient package

The Microsoft.Extensions.Caching.SqlServer package will use the new Microsoft.Data.SqlClient package instead of System.Data.SqlClient package. This change could cause slight behavioral breaking changes. For more information, see Introducing the new Microsoft.Data.SqlClient.

Version introduced

3.0

Old behavior

The Microsoft.Extensions.Caching.SqlServer package used the System.Data.SqlClient package.

New behavior

Microsoft.Extensions.Caching.SqlServer is now using the Microsoft.Data.SqlClient package.

Reason for change

Microsoft.Data.SqlClient is a new package that is built off of System.Data.SqlClient. It's where all new feature work will be done from now on.

Customers shouldn't need to worry about this breaking change unless they were using types returned by the Microsoft.Extensions.Caching.SqlServer package and casting them to System.Data.SqlClient types. For example, if someone was casting a DbConnection to the old SqlConnection type, they would need to change the cast to the new Microsoft.Data.SqlClient.SqlConnection type.

Category

ASP.NET Core

Affected APIs

None

Caching: ResponseCaching "pubternal" types changed to internal

In ASP.NET Core 3.0, "pubternal" types in ResponseCaching have been changed to internal.

In addition, default implementations of IResponseCachingPolicyProvider and IResponseCachingKeyProvider are no longer added to services as part of the AddResponseCaching method.

Change description

In ASP.NET Core, "pubternal" types are declared as public but reside in a namespace suffixed with .Internal. While these types are public, they have no support policy and are subject to breaking changes. Unfortunately, accidental use of these types has been common, resulting in breaking changes to these projects and limiting the ability to maintain the framework.

Version introduced

3.0

Old behavior

These types were publicly visible, but unsupported.

New behavior

These types are now internal.

Reason for change

The internal scope better reflects the unsupported policy.

Copy types that are used by your app or library.

Category

ASP.NET Core

Affected APIs

Data Protection: DataProtection.Blobs uses new Azure Storage APIs

Azure.Extensions.AspNetCore.DataProtection.Blobs depends on the Azure Storage libraries. These libraries renamed their assemblies, packages, and namespaces. Starting in ASP.NET Core 3.0, Azure.Extensions.AspNetCore.DataProtection.Blobs uses the new Azure.Storage.-prefixed APIs and packages.

For questions about the Azure Storage APIs, use https://github.com/Azure/azure-storage-net. For discussion on this issue, see dotnet/aspnetcore#19570.

Version introduced

3.0

Old behavior

The package referenced the WindowsAzure.Storage NuGet package. The package references the Microsoft.Azure.Storage.Blob NuGet package.

New behavior

The package references the Azure.Storage.Blob NuGet package.

Reason for change

This change allows Azure.Extensions.AspNetCore.DataProtection.Blobs to migrate to the recommended Azure Storage packages.

If you still need to use the older Azure Storage APIs with ASP.NET Core 3.0, add a direct dependency to the package WindowsAzure.Storage or Microsoft.Azure.Storage. This package can be installed alongside the new Azure.Storage APIs.

In many cases, the upgrade only involves changing the using statements to use the new namespaces:

- using Microsoft.WindowsAzure.Storage;
- using Microsoft.WindowsAzure.Storage.Blob;
- using Microsoft.Azure.Storage;
- using Microsoft.Azure.Storage.Blob;
+ using Azure.Storage;
+ using Azure.Storage.Blobs;

Category

ASP.NET Core

Affected APIs

None

Hosting: AspNetCoreModule V1 removed from Windows Hosting Bundle

Starting with ASP.NET Core 3.0, the Windows Hosting Bundle won't contain AspNetCoreModule (ANCM) V1.

ANCM V2 is backwards compatible with ANCM OutOfProcess and is recommended for use with ASP.NET Core 3.0 apps.

For discussion, see dotnet/aspnetcore#7095.

Version introduced

3.0

Old behavior

ANCM V1 is included in the Windows Hosting Bundle.

New behavior

ANCM V1 isn't included in the Windows Hosting Bundle.

Reason for change

ANCM V2 is backwards compatible with ANCM OutOfProcess and is recommended for use with ASP.NET Core 3.0 apps.

Use ANCM V2 with ASP.NET Core 3.0 apps.

If ANCM V1 is required, it can be installed using the ASP.NET Core 2.1 or 2.2 Windows Hosting Bundle.

This change will break ASP.NET Core 3.0 apps that:

  • Explicitly opted into using ANCM V1 with <AspNetCoreModuleName>AspNetCoreModule</AspNetCoreModuleName>.
  • Have a custom web.config file with <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />.

Category

ASP.NET Core

Affected APIs

None

Hosting: Generic host restricts Startup constructor injection

The only types the generic host supports for Startup class constructor injection are IHostEnvironment, IWebHostEnvironment, and IConfiguration. Apps using WebHost are unaffected.

Change description

Prior to ASP.NET Core 3.0, constructor injection could be used for arbitrary types in the Startup class's constructor. In ASP.NET Core 3.0, the web stack was replatformed onto the generic host library. You can see the change in the Program.cs file of the templates:

ASP.NET Core 2.x:

https://github.com/dotnet/aspnetcore/blob/5cb615fcbe8559e49042e93394008077e30454c0/src/Templating/src/Microsoft.DotNet.Web.ProjectTemplates/content/EmptyWeb-CSharp/Program.cs#L20-L22

ASP.NET Core 3.0:

https://github.com/dotnet/aspnetcore/blob/b1ca2c1155da3920f0df5108b9fedbe82efaa11c/src/ProjectTemplates/Web.ProjectTemplates/content/EmptyWeb-CSharp/Program.cs#L19-L24

Host uses one dependency injection (DI) container to build the app. WebHost uses two containers: one for the host and one for the app. As a result, the Startup constructor no longer supports custom service injection. Only IHostEnvironment, IWebHostEnvironment, and IConfiguration can be injected. This change prevents DI issues such as the duplicate creation of a singleton service.

Version introduced

3.0

Reason for change

This change is a consequence of replatforming the web stack onto the generic host library.

Inject services into the Startup.Configure method signature. For example:

public void Configure(IApplicationBuilder app, IOptions<MyOptions> options)

Category

ASP.NET Core

Affected APIs

None

Hosting: HTTPS redirection enabled for IIS out-of-process apps

Version 13.0.19218.0 of the ASP.NET Core Module (ANCM) for hosting via IIS out-of-process enables an existing HTTPS redirection feature for ASP.NET Core 3.0 and 2.2 apps.

For discussion, see dotnet/AspNetCore#15243.

Version introduced

3.0

Old behavior

The ASP.NET Core 2.1 project template first introduced support for HTTPS middleware methods like UseHttpsRedirection and UseHsts. Enabling HTTPS redirection required the addition of configuration, since apps in development don't use the default port of 443. HTTP Strict Transport Security (HSTS) is active only if the request is already using HTTPS. Localhost is skipped by default.

New behavior

In ASP.NET Core 3.0, the IIS HTTPS scenario was enhanced. With the enhancement, an app could discover the server's HTTPS ports and make UseHttpsRedirection work by default. The in-process component accomplished port discovery with the IServerAddresses feature, which only affects ASP.NET Core 3.0 apps because the in-process library is versioned with the framework. The out-of-process component changed to automatically add the ASPNETCORE_HTTPS_PORT environment variable. This change affected both ASP.NET Core 2.2 and 3.0 apps because the out-of-process component is shared globally. ASP.NET Core 2.1 apps aren't affected because they use a prior version of ANCM by default.

The preceding behavior was modified in ASP.NET Core 3.0.1 and 3.1.0 Preview 3 to reverse the behavior changes in ASP.NET Core 2.x. These changes only affect IIS out-of-process apps.

As detailed above, installing ASP.NET Core 3.0.0 had the side effect of also activating the UseHttpsRedirection middleware in ASP.NET Core 2.x apps. A change was made to ANCM in ASP.NET Core 3.0.1 and 3.1.0 Preview 3 such that installing them no longer has this effect on ASP.NET Core 2.x apps. The ASPNETCORE_HTTPS_PORT environment variable that ANCM populated in ASP.NET Core 3.0.0 was changed to ASPNETCORE_ANCM_HTTPS_PORT in ASP.NET Core 3.0.1 and 3.1.0 Preview 3. UseHttpsRedirection was also updated in these releases to understand both the new and old variables. ASP.NET Core 2.x won't be updated. As a result, it reverts to the previous behavior of being disabled by default.

Reason for change

Improved ASP.NET Core 3.0 functionality.

No action is required if you want all clients to use HTTPS. To allow some clients to use HTTP, take one of the following steps:

  • Remove the calls to UseHttpsRedirection and UseHsts from your project's Startup.Configure method, and redeploy the app.

  • In your web.config file, set the ASPNETCORE_HTTPS_PORT environment variable to an empty string. This change can occur directly on the server without redeploying the app. For example:

    <aspNetCore processPath="dotnet" arguments=".\WebApplication3.dll" stdoutLogEnabled="false" stdoutLogFile="\\?\%home%\LogFiles\stdout" >
    <environmentVariables>
    <environmentVariable name="ASPNETCORE_HTTPS_PORT" value="" />
    </environmentVariables>
</aspNetCore>

UseHttpsRedirection can still be:

  • Activated manually in ASP.NET Core 2.x by setting the ASPNETCORE_HTTPS_PORT environment variable to the appropriate port number (443 in most production scenarios).
  • Deactivated in ASP.NET Core 3.x by defining ASPNETCORE_ANCM_HTTPS_PORT with an empty string value. This value is set in the same fashion as the preceding ASPNETCORE_HTTPS_PORT example.

Machines running ASP.NET Core 3.0.0 apps should install the ASP.NET Core 3.0.1 runtime before installing the ASP.NET Core 3.1.0 Preview 3 ANCM. Doing so ensures that UseHttpsRedirection continues to operate as expected for the ASP.NET Core 3.0 apps.

In Azure App Service, ANCM deploys on a separate schedule from the runtime because of its global nature. ANCM was deployed to Azure with these changes after ASP.NET Core 3.0.1 and 3.1.0 were deployed.

Category

ASP.NET Core

Affected APIs

HttpsPolicyBuilderExtensions.UseHttpsRedirection(IApplicationBuilder)

Hosting: IHostingEnvironment and IApplicationLifetime types marked obsolete and replaced

New types have been introduced to replace existing IHostingEnvironment and IApplicationLifetime types.

Version introduced

3.0

Old behavior

There were two different IHostingEnvironment and IApplicationLifetime types from Microsoft.Extensions.Hosting and Microsoft.AspNetCore.Hosting.

New behavior

The old types have been marked as obsolete and replaced with new types.

Reason for change

When Microsoft.Extensions.Hosting was introduced in ASP.NET Core 2.1, some types like IHostingEnvironment and IApplicationLifetime were copied from Microsoft.AspNetCore.Hosting. Some ASP.NET Core 3.0 changes cause apps to include both the Microsoft.Extensions.Hosting and Microsoft.AspNetCore.Hosting namespaces. Any use of those duplicate types causes an "ambiguous reference" compiler error when both namespaces are referenced.

Replaced any usages of the old types with the newly introduced types as below:

Obsolete types (warning):

New types:

The new IHostEnvironment IsDevelopment and IsProduction extension methods are in the Microsoft.Extensions.Hosting namespace. That namespace may need to be added to your project.

Category

ASP.NET Core

Affected APIs

Hosting: ObjectPoolProvider removed from WebHostBuilder dependencies

As part of making ASP.NET Core more pay for play, the ObjectPoolProvider was removed from the main set of dependencies. Specific components relying on ObjectPoolProvider now add it themselves.

For discussion, see dotnet/aspnetcore#5944.

Version introduced

3.0

Old behavior

WebHostBuilder provides ObjectPoolProvider by default in the DI container.

New behavior

WebHostBuilder no longer provides ObjectPoolProvider by default in the DI container.

Reason for change

This change was made to make ASP.NET Core more pay for play.

If your component requires ObjectPoolProvider, it needs to be added to your dependencies via the IServiceCollection.

Category

ASP.NET Core

Affected APIs

None

HTTP: DefaultHttpContext extensibility removed

As part of ASP.NET Core 3.0 performance improvements, the extensibility of DefaultHttpContext was removed. The class is now sealed. For more information, see dotnet/aspnetcore#6504.

If your unit tests use Mock<DefaultHttpContext>, use Mock<HttpContext> or new DefaultHttpContext() instead.

For discussion, see dotnet/aspnetcore#6534.

Version introduced

3.0

Old behavior

Classes can derive from DefaultHttpContext.

New behavior

Classes can't derive from DefaultHttpContext.

Reason for change

The extensibility was provided initially to allow pooling of the HttpContext, but it introduced unnecessary complexity and impeded other optimizations.

If you're using Mock<DefaultHttpContext> in your unit tests, begin using Mock<HttpContext> instead.

Category

ASP.NET Core

Affected APIs

Microsoft.AspNetCore.Http.DefaultHttpContext

HTTP: HeaderNames constants changed to static readonly

Starting in ASP.NET Core 3.0 Preview 5, the fields in Microsoft.Net.Http.Headers.HeaderNames changed from const to static readonly.

For discussion, see dotnet/aspnetcore#9514.

Version introduced

3.0

Old behavior

These fields used to be const.

New behavior

These fields are now static readonly.

Reason for change

The change:

  • Prevents the values from being embedded across assembly boundaries, allowing for value corrections as needed.
  • Enables faster reference equality checks.

Recompile against 3.0. Source code using these fields in the following ways can no longer do so:

  • As an attribute argument
  • As a case in a switch statement
  • When defining another const

To work around the breaking change, switch to using self-defined header name constants or string literals.

Category

ASP.NET Core

Affected APIs

Microsoft.Net.Http.Headers.HeaderNames

HTTP: Response body infrastructure changes

The infrastructure backing an HTTP response body has changed. If you're using HttpResponse directly, you shouldn't need to make any code changes. Read further if you're wrapping or replacing HttpResponse.Body or accessing HttpContext.Features.

Version introduced

3.0

Old behavior

There were three APIs associated with the HTTP response body:

  • IHttpResponseFeature.Body
  • IHttpSendFileFeature.SendFileAsync
  • IHttpBufferingFeature.DisableResponseBuffering

New behavior

If you replace HttpResponse.Body, it replaces the entire IHttpResponseBodyFeature with a wrapper around your given stream using StreamResponseBodyFeature to provide default implementations for all of the expected APIs. Setting back the original stream reverts this change.

Reason for change

The motivation is to combine the response body APIs into a single new feature interface.

Use IHttpResponseBodyFeature where you previously were using IHttpResponseFeature.Body, IHttpSendFileFeature, or IHttpBufferingFeature.

Category

ASP.NET Core

Affected APIs

SameSite is an option for cookies that can help mitigate some Cross-Site Request Forgery (CSRF) attacks. When this option was initially introduced, inconsistent defaults were used across various ASP.NET Core APIs. The inconsistency has led to confusing results. As of ASP.NET Core 3.0, these defaults are better aligned. You must opt in to this feature on a per-component basis.

Version introduced

3.0

Old behavior

Similar ASP.NET Core APIs used different default SameSiteMode values. An example of the inconsistency is seen in HttpResponse.Cookies.Append(String, String) and HttpResponse.Cookies.Append(String, String, CookieOptions), which defaulted to SameSiteMode.None and SameSiteMode.Lax, respectively.

New behavior

All the affected APIs default to SameSiteMode.None.

Reason for change

The default value was changed to make SameSite an opt-in feature.

Each component that emits cookies needs to decide if SameSite is appropriate for its scenarios. Review your usage of the affected APIs and reconfigure SameSite as needed.

Category

ASP.NET Core

Affected APIs

HTTP: Synchronous IO disabled in all servers

Starting with ASP.NET Core 3.0, synchronous server operations are disabled by default.

Change description

AllowSynchronousIO is an option in each server that enables or disables synchronous IO APIs like HttpRequest.Body.Read, HttpResponse.Body.Write, and Stream.Flush. These APIs have long been a source of thread starvation and app hangs. Starting in ASP.NET Core 3.0 Preview 3, these synchronous operations are disabled by default.

Affected servers:

  • Kestrel
  • HttpSys
  • IIS in-process
  • TestServer

Expect errors similar to:

  • Synchronous operations are disallowed. Call ReadAsync or set AllowSynchronousIO to true instead.
  • Synchronous operations are disallowed. Call WriteAsync or set AllowSynchronousIO to true instead.
  • Synchronous operations are disallowed. Call FlushAsync or set AllowSynchronousIO to true instead.

Each server has an AllowSynchronousIO option that controls this behavior and the default for all of them is now false.

The behavior can also be overridden on a per-request basis as a temporary mitigation. For example:

var syncIOFeature = HttpContext.Features.Get<IHttpBodyControlFeature>();
if (syncIOFeature != null)
{
    syncIOFeature.AllowSynchronousIO = true;
}

If you have trouble with a TextWriter or another stream calling a synchronous API in Dispose, call the new DisposeAsync API instead.

For discussion, see dotnet/aspnetcore#7644.

Version introduced

3.0

Old behavior

HttpRequest.Body.Read, HttpResponse.Body.Write, and Stream.Flush were allowed by default.

New behavior

These synchronous APIs are disallowed by default:

Expect errors similar to:

  • Synchronous operations are disallowed. Call ReadAsync or set AllowSynchronousIO to true instead.
  • Synchronous operations are disallowed. Call WriteAsync or set AllowSynchronousIO to true instead.
  • Synchronous operations are disallowed. Call FlushAsync or set AllowSynchronousIO to true instead.

Reason for change

These synchronous APIs have long been a source of thread starvation and app hangs. Starting in ASP.NET Core 3.0 Preview 3, the synchronous operations are disabled by default.

Use the asynchronous versions of the methods. The behavior can also be overridden on a per-request basis as a temporary mitigation.

var syncIOFeature = HttpContext.Features.Get<IHttpBodyControlFeature>();
if (syncIOFeature != null)
{
    syncIOFeature.AllowSynchronousIO = true;
}

Category

ASP.NET Core

Affected APIs

Identity: AddDefaultUI method overload removed

Starting with ASP.NET Core 3.0, the IdentityBuilderUIExtensions.AddDefaultUI(IdentityBuilder,UIFramework) method overload no longer exists.

Version introduced

3.0

Reason for change

This change was a result of adoption of the static web assets feature.

Call IdentityBuilderUIExtensions.AddDefaultUI(IdentityBuilder) instead of the overload that takes two arguments. If you're using Bootstrap 3, also add the following line to a <PropertyGroup> element in your project file:

<IdentityUIFrameworkVersion>Bootstrap3</IdentityUIFrameworkVersion>

Category

ASP.NET Core

Affected APIs

IdentityBuilderUIExtensions.AddDefaultUI(IdentityBuilder,UIFramework)

Identity: Default Bootstrap version of UI changed

Starting in ASP.NET Core 3.0, Identity UI defaults to using version 4 of Bootstrap.

Version introduced

3.0

Old behavior

The services.AddDefaultIdentity<IdentityUser>().AddDefaultUI(); method call was the same as services.AddDefaultIdentity<IdentityUser>().AddDefaultUI(UIFramework.Bootstrap3);

New behavior

The services.AddDefaultIdentity<IdentityUser>().AddDefaultUI(); method call is the same as services.AddDefaultIdentity<IdentityUser>().AddDefaultUI(UIFramework.Bootstrap4);

Reason for change

Bootstrap 4 was released during ASP.NET Core 3.0 timeframe.

You're impacted by this change if you use the default Identity UI and have added it in Startup.ConfigureServices as shown in the following example:

services.AddDefaultIdentity<IdentityUser>().AddDefaultUI();

Take one of the following actions:

  • Migrate your app to use Bootstrap 4 using their migration guide.

  • Update Startup.ConfigureServices to enforce usage of Bootstrap 3. For example:

    services.AddDefaultIdentity<IdentityUser>().AddDefaultUI(UIFramework.Bootstrap3);

Category

ASP.NET Core

Affected APIs

None

Identity: SignInAsync throws exception for unauthenticated identity

By default, SignInAsync throws an exception for principals / identities in which IsAuthenticated is false.

Version introduced

3.0

Old behavior

SignInAsync accepts any principals / identities, including identities in which IsAuthenticated is false.

New behavior

By default, SignInAsync throws an exception for principals / identities in which IsAuthenticated is false. There's a new flag to suppress this behavior, but the default behavior has changed.

Reason for change

The old behavior was problematic because, by default, these principals were rejected by [Authorize] / RequireAuthenticatedUser().

In ASP.NET Core 3.0 Preview 6, there's a RequireAuthenticatedSignIn flag on AuthenticationOptions that is true by default. Set this flag to false to restore the old behavior.

Category

ASP.NET Core

Affected APIs

None

Identity: SignInManager constructor accepts new parameter

Starting with ASP.NET Core 3.0, a new IUserConfirmation<TUser> parameter was added to the SignInManager constructor. For more information, see dotnet/aspnetcore#8356.

Version introduced

3.0

Reason for change

The motivation for the change was to add support for new email / confirmation flows in Identity.

If manually constructing a SignInManager, provide an implementation of IUserConfirmation or grab one from dependency injection to provide.

Category

ASP.NET Core

Affected APIs

SignInManager<TUser>

Identity: UI uses static web assets feature

ASP.NET Core 3.0 introduced a static web assets feature, and Identity UI has adopted it.

Change description

As a result of Identity UI adopting the static web assets feature:

  • Framework selection is accomplished by using the IdentityUIFrameworkVersion property in your project file.
  • Bootstrap 4 is the default UI framework for Identity UI. Bootstrap 3 has reached end of life, and you should consider migrating to a supported version.

Version introduced

3.0

Old behavior

The default UI framework for Identity UI was Bootstrap 3. The UI framework could be configured using a parameter to the AddDefaultUI method call in Startup.ConfigureServices.

New behavior

The default UI framework for Identity UI is Bootstrap 4. The UI framework must be configured in your project file, instead of in the AddDefaultUI method call.

Reason for change

Adoption of the static web assets feature required that the UI framework configuration move to MSBuild. The decision on which framework to embed is a build-time decision, not a runtime decision.

Review your site UI to ensure the new Bootstrap 4 components are compatible. If necessary, use the IdentityUIFrameworkVersion MSBuild property to revert to Bootstrap 3. Add the property to a <PropertyGroup> element in your project file:

<IdentityUIFrameworkVersion>Bootstrap3</IdentityUIFrameworkVersion>

Category

ASP.NET Core

Affected APIs

IdentityBuilderUIExtensions.AddDefaultUI(IdentityBuilder, UIFramework)

Kestrel: Connection adapters removed

As part of the move to move "pubternal" APIs to public, the concept of an IConnectionAdapter was removed from Kestrel. Connection adapters are being replaced with connection middleware (similar to HTTP middleware in the ASP.NET Core pipeline, but for lower-level connections). HTTPS and connection logging have moved from connection adapters to connection middleware. Those extension methods should continue to work seamlessly, but the implementation details have changed.

For more information, see dotnet/aspnetcore#11412. For discussion, see dotnet/aspnetcore#11475.

Version introduced

3.0

Old behavior

Kestrel extensibility components were created using IConnectionAdapter.

New behavior

Kestrel extensibility components are created as middleware.

Reason for change

This change is intended to provide a more flexible extensibility architecture.

Convert any implementations of IConnectionAdapter to use the new middleware pattern as shown here.

Category

ASP.NET Core

Affected APIs

Microsoft.AspNetCore.Server.Kestrel.Core.Adapter.Internal.IConnectionAdapter

Kestrel: Empty HTTPS assembly removed

The assembly Microsoft.AspNetCore.Server.Kestrel.Https has been removed.

Version introduced

3.0

Reason for change

In ASP.NET Core 2.1, the contents of Microsoft.AspNetCore.Server.Kestrel.Https were moved to Microsoft.AspNetCore.Server.Kestrel.Core. This change was done in a non-breaking way using [TypeForwardedTo] attributes.

  • Libraries referencing Microsoft.AspNetCore.Server.Kestrel.Https 2.0 should update all ASP.NET Core dependencies to 2.1 or later. Otherwise, they may break when loaded into an ASP.NET Core 3.0 app.
  • Apps and libraries targeting ASP.NET Core 2.1 and later should remove any direct references to the Microsoft.AspNetCore.Server.Kestrel.Https NuGet package.

Category

ASP.NET Core

Affected APIs

None

Kestrel: Request trailer headers moved to new collection

In prior versions, Kestrel added HTTP/1.1 chunked trailer headers into the request headers collection when the request body was read to the end. This behavior caused concerns about ambiguity between headers and trailers. The decision was made to move the trailers to a new collection.

HTTP/2 request trailers were unavailable in ASP.NET Core 2.2 but are now also available in this new collection in ASP.NET Core 3.0.

New request extension methods have been added to access these trailers.

HTTP/1.1 trailers are available once the entire request body has been read.

HTTP/2 trailers are available once they're received from the client. The client won't send the trailers until the entire request body has been at least buffered by the server. You may need to read the request body to free up buffer space. Trailers are always available if you read the request body to the end. The trailers mark the end of the body.

Version introduced

3.0

Old behavior

Request trailer headers would be added to the HttpRequest.Headers collection.

New behavior

Request trailer headers aren't present in the HttpRequest.Headers collection. Use the following extension methods on HttpRequest to access them:

  • GetDeclaredTrailers() - Gets the request "Trailer" header that lists which trailers to expect after the body.
  • SupportsTrailers() - Indicates if the request supports receiving trailer headers.
  • CheckTrailersAvailable() - Determines if the request supports trailers and if they're available for reading.
  • GetTrailer(string trailerName) - Gets the requested trailing header from the response.

Reason for change

Trailers are a key feature in scenarios like gRPC. Merging the trailers in to request headers was confusing to users.

Use the trailer-related extension methods on HttpRequest to access trailers.

Category

ASP.NET Core

Affected APIs

HttpRequest.Headers

Kestrel: Transport abstractions removed and made public

As part of moving away from "pubternal" APIs, the Kestrel transport layer APIs are exposed as a public interface in the Microsoft.AspNetCore.Connections.Abstractions library.

Version introduced

3.0

Old behavior

  • Transport-related abstractions were available in the Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions library.
  • The ListenOptions.NoDelay property was available.

New behavior

  • The IConnectionListener interface was introduced in the Microsoft.AspNetCore.Connections.Abstractions library to expose the most used functionality from the ...Transport.Abstractions library.
  • The NoDelay is now available in transport options (LibuvTransportOptions and SocketTransportOptions).
  • SchedulingMode is no longer available.

Reason for change

ASP.NET Core 3.0 has moved away from "pubternal" APIs.

Category

ASP.NET Core

Affected APIs

None

Localization: ResourceManagerWithCultureStringLocalizer and WithCulture marked obsolete

The ResourceManagerWithCultureStringLocalizer class and WithCulture interface member are often sources of confusion for users of localization, especially when creating their own IStringLocalizer implementation. These items give the user the impression that an IStringLocalizer instance is "per-language, per-resource". In reality, the instances should only be "per-resource". The language searched for is determined by the CultureInfo.CurrentUICulture at execution time. To eliminate the source of confusion, the APIs were marked as obsolete in ASP.NET Core 3.0. The APIs will be removed in a future release.

For context, see dotnet/aspnetcore#3324. For discussion, see dotnet/aspnetcore#7756.

Version introduced

3.0

Old behavior

Methods weren't marked as Obsolete.

New behavior

Methods are marked Obsolete.

Reason for change

The APIs represented a use case that isn't recommended. There was confusion about the design of localization.

The recommendation is to use ResourceManagerStringLocalizer instead. Let the culture be set by the CurrentCulture. If that isn't an option, create and use a copy of ResourceManagerWithCultureStringLocalizer.

Category

ASP.NET Core

Affected APIs

  • Microsoft.Extensions.Localization.ResourceManagerWithCultureStringLocalizer
  • Microsoft.Extensions.Localization.ResourceManagerStringLocalizer.WithCulture

Logging: DebugLogger class made internal

Prior to ASP.NET Core 3.0, DebugLogger's access modifier was public. In ASP.NET Core 3.0, the access modifier changed to internal.

Version introduced

3.0

Reason for change

The change is being made to:

  • Enforce consistency with other logger implementations such as ConsoleLogger.
  • Reduce the API surface.

Use the AddDebug ILoggingBuilder extension method to enable debug logging. DebugLoggerProvider is also still public in the event the service needs to be registered manually.

Category

ASP.NET Core

Affected APIs

Microsoft.Extensions.Logging.Debug.DebugLogger

MVC: Async suffix trimmed from controller action names

As part of addressing dotnet/aspnetcore#4849, ASP.NET Core MVC trims the suffix Async from action names by default. Starting with ASP.NET Core 3.0, this change affects both routing and link generation.

Version introduced

3.0

Old behavior

Consider the following ASP.NET Core MVC controller:

public class ProductController : Controller
{
    public async IActionResult ListAsync()
    {
        var model = await DbContext.Products.ToListAsync();
        return View(model);
    }
}

The action is routable via Product/ListAsync. Link generation requires specifying the Async suffix. For example:

<a asp-controller="Product" asp-action="ListAsync">List</a>

New behavior

In ASP.NET Core 3.0, the action is routable via Product/List. Link generation code should omit the Async suffix. For example:

<a asp-controller="Product" asp-action="List">List</a>

This change doesn't affect names specified using the [ActionName] attribute. The new behavior can be disabled by setting MvcOptions.SuppressAsyncSuffixInActionNames to false in Startup.ConfigureServices:

services.AddMvc(options =>
{
   options.SuppressAsyncSuffixInActionNames = false;
});

Reason for change

By convention, asynchronous .NET methods are suffixed with Async. However, when a method defines an MVC action, it's undesirable to use the Async suffix.

If your app depends on MVC actions preserving the name's Async suffix, choose one of the following mitigations:

  • Use the [ActionName] attribute to preserve the original name.
  • Disable the renaming entirely by setting MvcOptions.SuppressAsyncSuffixInActionNames to false in Startup.ConfigureServices:
services.AddMvc(options =>
{
   options.SuppressAsyncSuffixInActionNames = false;
});

Category

ASP.NET Core

Affected APIs

None

MVC: JsonResult moved to Microsoft.AspNetCore.Mvc.Core

JsonResult has moved to the Microsoft.AspNetCore.Mvc.Core assembly. This type used to be defined in Microsoft.AspNetCore.Mvc.Formatters.Json. An assembly-level [TypeForwardedTo] attribute was added to Microsoft.AspNetCore.Mvc.Formatters.Json to address this issue for the majority of users. Apps that use third-party libraries may encounter issues.

Version introduced

3.0 Preview 6

Old behavior

An app using a 2.2-based library builds successfully.

New behavior

An app using a 2.2-based library fails compilation. An error containing a variation of the following text is provided:

The type 'JsonResult' exists in both 'Microsoft.AspNetCore.Mvc.Core, Version=3.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' and 'Microsoft.AspNetCore.Mvc.Formatters.Json, Version=2.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'

For an example of such an issue, see dotnet/aspnetcore#7220.

Reason for change

Platform-level changes to the composition of ASP.NET Core as described at aspnet/Announcements#325.

Libraries compiled against the 2.2 version of Microsoft.AspNetCore.Mvc.Formatters.Json may need to recompile to address the problem for all consumers. If affected, contact the library author. Request recompilation of the library to target ASP.NET Core 3.0.

Category

ASP.NET Core

Affected APIs

Microsoft.AspNetCore.Mvc.JsonResult

MVC: Precompilation tool deprecated

In ASP.NET Core 1.1, the Microsoft.AspNetCore.Mvc.Razor.ViewCompilation (MVC precompilation tool) package was introduced to add support for publish-time compilation of Razor files (.cshtml files). In ASP.NET Core 2.1, the Razor SDK was introduced to expand upon features of the precompilation tool. The Razor SDK added support for build- and publish-time compilation of Razor files. The SDK verifies the correctness of .cshtml files at build time while improving on app startup time. The Razor SDK is on by default, and no gesture is required to start using it.

In ASP.NET Core 3.0, the ASP.NET Core 1.1-era MVC precompilation tool was removed. Earlier package versions will continue receiving important bug and security fixes in the patch release.

Version introduced

3.0

Old behavior

The Microsoft.AspNetCore.Mvc.Razor.ViewCompilation package was used to pre-compile MVC Razor views.

New behavior

The Razor SDK natively supports this functionality. The Microsoft.AspNetCore.Mvc.Razor.ViewCompilation package is no longer updated.

Reason for change

The Razor SDK provides more functionality and verifies the correctness of .cshtml files at build time. The SDK also improves app startup time.

For users of ASP.NET Core 2.1 or later, update to use the native support for precompilation in the Razor SDK. If bugs or missing features prevent migration to the Razor SDK, open an issue at dotnet/aspnetcore.

Category

ASP.NET Core

Affected APIs

None

MVC: "Pubternal" types changed to internal

In ASP.NET Core 3.0, all "pubternal" types in MVC were updated to either be public in a supported namespace or internal as appropriate.

Change description

In ASP.NET Core, "pubternal" types are declared as public but reside in a .Internal-suffixed namespace. While these types are public, they have no support policy and are subject to breaking changes. Unfortunately, accidental use of these types has been common, resulting in breaking changes to these projects and limiting the ability to maintain the framework.

Version introduced

3.0

Old behavior

Some types in MVC were public but in a .Internal namespace. These types had no support policy and were subject to breaking changes.

New behavior

All such types are updated either to be public in a supported namespace or marked as internal.

Reason for change

Accidental use of the "pubternal" types has been common, resulting in breaking changes to these projects and limiting the ability to maintain the framework.

If you're using types that have become truly public and have been moved into a new, supported namespace, update your references to match the new namespaces.

If you're using types that have become marked as internal, you'll need to find an alternative. The previously "pubternal" types were never supported for public use. If there are specific types in these namespaces that are critical to your apps, file an issue at dotnet/aspnetcore. Considerations may be made for making the requested types public.

Category

ASP.NET Core

Affected APIs

This change includes types in the following namespaces:

  • Microsoft.AspNetCore.Mvc.Cors.Internal
  • Microsoft.AspNetCore.Mvc.DataAnnotations.Internal
  • Microsoft.AspNetCore.Mvc.Formatters.Internal
  • Microsoft.AspNetCore.Mvc.Formatters.Json.Internal
  • Microsoft.AspNetCore.Mvc.Formatters.Xml.Internal
  • Microsoft.AspNetCore.Mvc.Internal
  • Microsoft.AspNetCore.Mvc.ModelBinding.Internal
  • Microsoft.AspNetCore.Mvc.Razor.Internal
  • Microsoft.AspNetCore.Mvc.RazorPages.Internal
  • Microsoft.AspNetCore.Mvc.TagHelpers.Internal
  • Microsoft.AspNetCore.Mvc.ViewFeatures.Internal

MVC: Web API compatibility shim removed

Starting with ASP.NET Core 3.0, the Microsoft.AspNetCore.Mvc.WebApiCompatShim package is no longer available.

Change description

The Microsoft.AspNetCore.Mvc.WebApiCompatShim (WebApiCompatShim) package provides partial compatibility in ASP.NET Core with ASP.NET 4.x Web API 2 to simplify migrating existing Web API implementations to ASP.NET Core. However, apps using the WebApiCompatShim don't benefit from the API-related features shipping in recent ASP.NET Core releases. Such features include improved Open API specification generation, standardized error handling, and client code generation. To better focus the API efforts in 3.0, WebApiCompatShim was removed. Existing apps using the WebApiCompatShim should migrate to the newer [ApiController] model.

Version introduced

3.0

Reason for change

The Web API compatibility shim was a migration tool. It restricts user access to new functionality added in ASP.NET Core.

Remove usage of this shim and migrate directly to the similar functionality in ASP.NET Core itself.

Category

ASP.NET Core

Affected APIs

Microsoft.AspNetCore.Mvc.WebApiCompatShim

Razor: RazorTemplateEngine API removed

The RazorTemplateEngine API was removed and replaced with Microsoft.AspNetCore.Razor.Language.RazorProjectEngine.

For discussion, see GitHub issue dotnet/aspnetcore#25215.

Version introduced

3.0

Old behavior

A template engine can be created and used to parse and generate code for Razor files.

New behavior

RazorProjectEngine can be created and provided the same type of information as RazorTemplateEngine to parse and generate code for Razor files. RazorProjectEngine also provides extra levels of configuration.

Reason for change

RazorTemplateEngine was too tightly coupled to the existing implementations. This tight coupling led to more questions when trying to properly configure a Razor parsing/generation pipeline.

Use RazorProjectEngine instead of RazorTemplateEngine. Consider the following examples.

Create and configure the RazorProjectEngine
RazorProjectEngine projectEngine =
    RazorProjectEngine.Create(RazorConfiguration.Default,
        RazorProjectFileSystem.Create(@"C:\source\repos\ConsoleApp4\ConsoleApp4"),
        builder =>
        {
            builder.ConfigureClass((document, classNode) =>
            {
                classNode.ClassName = "MyClassName";

                // Can also configure other aspects of the class here.
            });

            // More configuration can go here
        });
Generate code for a Razor file
RazorProjectItem item = projectEngine.FileSystem.GetItem(
    @"C:\source\repos\ConsoleApp4\ConsoleApp4\Example.cshtml",
    FileKinds.Legacy);
RazorCodeDocument output = projectEngine.Process(item);

// Things available
RazorSyntaxTree syntaxTree = output.GetSyntaxTree();
DocumentIntermediateNode intermediateDocument =
    output.GetDocumentIntermediateNode();
RazorCSharpDocument csharpDocument = output.GetCSharpDocument();

Category

ASP.NET Core

Affected APIs

  • RazorTemplateEngine
  • RazorTemplateEngineOptions

Razor: Runtime compilation moved to a package

Support for runtime compilation of Razor views and Razor Pages has moved to a separate package.

Version introduced

3.0

Old behavior

Runtime compilation is available without needing additional packages.

New behavior

The functionality has been moved to the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation package.

The following APIs were previously available in Microsoft.AspNetCore.Mvc.Razor.RazorViewEngineOptions to support runtime compilation. The APIs are now available via Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.MvcRazorRuntimeCompilationOptions.

  • RazorViewEngineOptions.FileProviders is now MvcRazorRuntimeCompilationOptions.FileProviders
  • RazorViewEngineOptions.AdditionalCompilationReferences is now MvcRazorRuntimeCompilationOptions.AdditionalReferencePaths

In addition, Microsoft.AspNetCore.Mvc.Razor.RazorViewEngineOptions.AllowRecompilingViewsOnFileChange has been removed. Recompilation on file changes is enabled by default by referencing the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation package.

Reason for change

This change was necessary to remove the ASP.NET Core shared framework dependency on Roslyn.

Apps that require runtime compilation or recompilation of Razor files should take the following steps:

  1. Add a reference to the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation package.

  2. Update the project's Startup.ConfigureServices method to include a call to AddRazorRuntimeCompilation. For example:

    services.AddMvc()
    .AddRazorRuntimeCompilation();

Category

ASP.NET Core

Affected APIs

Microsoft.AspNetCore.Mvc.Razor.RazorViewEngineOptions

Session state: Obsolete APIs removed

Obsolete APIs for configuring session cookies were removed. For more information, see aspnet/Announcements#257.

Version introduced

3.0

Reason for change

This change enforces consistency across APIs for configuring features that use cookies.

Migrate usage of the removed APIs to their newer replacements. Consider the following example in Startup.ConfigureServices:

public void ConfigureServices(ServiceCollection services)
{
    services.AddSession(options =>
    {
        // Removed obsolete APIs
        options.CookieName = "SessionCookie";
        options.CookieDomain = "contoso.com";
        options.CookiePath = "/";
        options.CookieHttpOnly = true;
        options.CookieSecure = CookieSecurePolicy.Always;

        // new API
        options.Cookie.Name = "SessionCookie";
        options.Cookie.Domain = "contoso.com";
        options.Cookie.Path = "/";
        options.Cookie.HttpOnly = true;
        options.Cookie.SecurePolicy = CookieSecurePolicy.Always;
    });
}

Category

ASP.NET Core

Affected APIs

Shared framework: Assemblies removed from Microsoft.AspNetCore.App

Starting in ASP.NET Core 3.0, the ASP.NET Core shared framework (Microsoft.AspNetCore.App) only contains first-party assemblies that are fully developed, supported, and serviceable by Microsoft.

Change description

Think of the change as the redefining of boundaries for the ASP.NET Core "platform." The shared framework will be source-buildable by anybody via GitHub and will continue to offer the existing benefits of .NET Core shared frameworks to your apps. Some benefits include smaller deployment size, centralized patching, and faster startup time.

As part of the change, some notable breaking changes are introduced in Microsoft.AspNetCore.App.

Version introduced

3.0

Old behavior

Projects referenced Microsoft.AspNetCore.App via a <PackageReference> element in the project file.

Additionally, Microsoft.AspNetCore.App contained the following subcomponents:

  • Json.NET (Newtonsoft.Json)
  • Entity Framework Core (assemblies prefixed with Microsoft.EntityFrameworkCore.)
  • Roslyn (Microsoft.CodeAnalysis)

New behavior

A reference to Microsoft.AspNetCore.App no longer requires a <PackageReference> element in the project file. The .NET Core SDK supports a new element called <FrameworkReference>, which replaces the use of <PackageReference>.

For more information, see dotnet/aspnetcore#3612.

Entity Framework Core ships as NuGet packages. This change aligns the shipping model with all other data access libraries on .NET. It provides Entity Framework Core the simplest path to continue innovating while supporting the various .NET platforms. The move of Entity Framework Core out of the shared framework has no impact on its status as a Microsoft-developed, supported, and serviceable library. The .NET Core support policy continues to cover it.

Json.NET and Entity Framework Core continue to work with ASP.NET Core. They won't, however, be included in the shared framework.

For more information, see The future of JSON in .NET Core 3.0. Also see the complete list of binaries removed from the shared framework.

Reason for change

This change simplifies the consumption of Microsoft.AspNetCore.App and reduces the duplication between NuGet packages and shared frameworks.

For more information on the motivation for this change, see this blog post.

Starting with ASP.NET Core 3.0, it is no longer necessary for projects to consume assemblies in Microsoft.AspNetCore.App as NuGet packages. To simplify the targeting and usage of the ASP.NET Core shared framework, many NuGet packages shipped since ASP.NET Core 1.0 are no longer produced. The APIs those packages provide are still available to apps by using a <FrameworkReference> to Microsoft.AspNetCore.App. Common API examples include Kestrel, MVC, and Razor.

This change doesn't apply to all binaries referenced via Microsoft.AspNetCore.App in ASP.NET Core 2.x. Notable exceptions include:

For more information, see Stop producing packages for shared framework assemblies in 3.0. For discussion, see dotnet/aspnetcore#3757.

Category

ASP.NET Core

Affected APIs

Shared framework: Removed Microsoft.AspNetCore.All

Starting in ASP.NET Core 3.0, the Microsoft.AspNetCore.All metapackage and the matching Microsoft.AspNetCore.All shared framework are no longer produced. This package is available in ASP.NET Core 2.2 and will continue to receive servicing updates in ASP.NET Core 2.1.

Version introduced

3.0

Old behavior

Apps could use the Microsoft.AspNetCore.All metapackage to target the Microsoft.AspNetCore.All shared framework on .NET Core.

New behavior

.NET Core 3.0 doesn't include a Microsoft.AspNetCore.All shared framework.

Reason for change

The Microsoft.AspNetCore.All metapackage included a large number of external dependencies.

Migrate your project to use the Microsoft.AspNetCore.App framework. Components that were previously available in Microsoft.AspNetCore.All are still available on NuGet. Those components are now deployed with your app instead of being included in the shared framework.

Category

ASP.NET Core

Affected APIs

None

SignalR: HandshakeProtocol.SuccessHandshakeData replaced

The HandshakeProtocol.SuccessHandshakeData field was removed and replaced with a helper method that generates a successful handshake response given a specific IHubProtocol.

Version introduced

3.0

Old behavior

HandshakeProtocol.SuccessHandshakeData was a public static ReadOnlyMemory<byte> field.

New behavior

HandshakeProtocol.SuccessHandshakeData has been replaced by a static GetSuccessfulHandshake(IHubProtocol protocol) method that returns a ReadOnlyMemory<byte> based on the specified protocol.

Reason for change

Additional fields were added to the handshake response that are non-constant and change depending on the selected protocol.

None. This type isn't designed for use from user code. It's public, so it can be shared between the SignalR server and client. It may also be used by customer SignalR clients written in .NET. Users of SignalR shouldn't be affected by this change.

Category

ASP.NET Core

Affected APIs

HandshakeProtocol.SuccessHandshakeData

SignalR: HubConnection ResetSendPing and ResetTimeout methods removed

The ResetSendPing and ResetTimeout methods were removed from the SignalR HubConnection API. These methods were originally intended only for internal use but were made public in ASP.NET Core 2.2. These methods won't be available starting in the ASP.NET Core 3.0 Preview 4 release. For discussion, see dotnet/aspnetcore#8543.

Version introduced

3.0

Old behavior

APIs were available.

New behavior

APIs are removed.

Reason for change

These methods were originally intended only for internal use but were made public in ASP.NET Core 2.2.

Don't use these methods.

Category

ASP.NET Core

Affected APIs

SignalR: HubConnectionContext constructors changed

SignalR's HubConnectionContext constructors changed to accept an options type, rather than multiple parameters, to future-proof adding options. This change replaces two constructors with a single constructor that accepts an options type.

Version introduced

3.0

Old behavior

HubConnectionContext has two constructors:

public HubConnectionContext(ConnectionContext connectionContext, TimeSpan keepAliveInterval, ILoggerFactory loggerFactory);
public HubConnectionContext(ConnectionContext connectionContext, TimeSpan keepAliveInterval, ILoggerFactory loggerFactory, TimeSpan clientTimeoutInterval);

New behavior

The two constructors were removed and replaced with one constructor:

public HubConnectionContext(ConnectionContext connectionContext, HubConnectionContextOptions contextOptions, ILoggerFactory loggerFactory)

Reason for change

The new constructor uses a new options object. Consequently, the features of HubConnectionContext can be expanded in the future without making more constructors and breaking changes.

Instead of using the following constructor:

HubConnectionContext connectionContext = new HubConnectionContext(
    connectionContext,
    keepAliveInterval: TimeSpan.FromSeconds(15),
    loggerFactory,
    clientTimeoutInterval: TimeSpan.FromSeconds(15));

Use the following constructor:

HubConnectionContextOptions contextOptions = new HubConnectionContextOptions()
{
    KeepAliveInterval = TimeSpan.FromSeconds(15),
    ClientTimeoutInterval = TimeSpan.FromSeconds(15)
};
HubConnectionContext connectionContext = new HubConnectionContext(connectionContext, contextOptions, loggerFactory);

Category

ASP.NET Core

Affected APIs

SignalR: JavaScript client package name changed

In ASP.NET Core 3.0 Preview 7, the SignalR JavaScript client package name changed from @aspnet/signalr to @microsoft/signalr. The name change reflects the fact that SignalR is useful in more than just ASP.NET Core apps, thanks to the Azure SignalR Service.

To react to this change, change references in your package.json files, require statements, and ECMAScript import statements. No API will change as part of this rename.

For discussion, see dotnet/aspnetcore#11637.

Version introduced

3.0

Old behavior

The client package was named @aspnet/signalr.

New behavior

The client package is named @microsoft/signalr.

Reason for change

The name change clarifies that SignalR is useful beyond ASP.NET Core apps, thanks to the Azure SignalR Service.

Switch to the new package @microsoft/signalr.

Category

ASP.NET Core

Affected APIs

None

SignalR: UseSignalR and UseConnections methods marked obsolete

The methods UseConnections and UseSignalR and the classes ConnectionsRouteBuilder and HubRouteBuilder are marked as obsolete in ASP.NET Core 3.0.

Version introduced

3.0

Old behavior

SignalR hub routing was configured using UseSignalR or UseConnections.

New behavior

The old way of configuring routing has been obsoleted and replaced with endpoint routing.

Reason for change

Middleware is being moved to the new endpoint routing system. The old way of adding middleware is being obsoleted.

Replace UseSignalR with UseEndpoints:

Old code:

app.UseSignalR(routes =>
{
    routes.MapHub<SomeHub>("/path");
});

New code:

app.UseEndpoints(endpoints =>
{
    endpoints.MapHub<SomeHub>("/path");
});

Category

ASP.NET Core

Affected APIs

SPAs: SpaServices and NodeServices marked obsolete

The contents of the following NuGet packages have all been unnecessary since ASP.NET Core 2.1. Consequently, the following packages are being marked as obsolete:

For the same reason, the following npm modules are being marked as deprecated:

The preceding packages and npm modules will later be removed in .NET 5.

Version introduced

3.0

Old behavior

The deprecated packages and npm modules were intended to integrate ASP.NET Core with various Single-Page App (SPA) frameworks. Such frameworks include Angular, React, and React with Redux.

New behavior

A new integration mechanism exists in the Microsoft.AspNetCore.SpaServices.Extensions NuGet package. The package remains the basis of the Angular and React project templates since ASP.NET Core 2.1.

Reason for change

ASP.NET Core supports integration with various Single-Page App (SPA) frameworks, including Angular, React, and React with Redux. Initially, integration with these frameworks was accomplished with ASP.NET Core-specific components that handled scenarios like server-side prerendering and integration with Webpack. As time went on, industry standards changed. Each of the SPA frameworks released their own standard command-line interfaces. For example, Angular CLI and create-react-app.

When ASP.NET Core 2.1 was released in May 2018, the team responded to the change in standards. A newer and simpler way to integrate with the SPA frameworks' own toolchains was provided. The new integration mechanism exists in the package Microsoft.AspNetCore.SpaServices.Extensions and remains the basis of the Angular and React project templates since ASP.NET Core 2.1.

To clarify that the older ASP.NET Core-specific components are irrelevant and not recommended:

  • The pre-2.1 integration mechanism is marked as obsolete.
  • The supporting npm packages are marked as deprecated.

If you're using these packages, update your apps to use the functionality:

  • In the Microsoft.AspNetCore.SpaServices.Extensions package.
  • Provided by the SPA frameworks you're using

To enable features like server-side prerendering and hot module reload, see the documentation for the corresponding SPA framework. The functionality in Microsoft.AspNetCore.SpaServices.Extensions is not obsolete and will continue to be supported.

Category

ASP.NET Core

Affected APIs

SPAs: SpaServices and NodeServices no longer fall back to console logger

Microsoft.AspNetCore.SpaServices and Microsoft.AspNetCore.NodeServices won't display console logs unless logging is configured.

Version introduced

3.0

Old behavior

Microsoft.AspNetCore.SpaServices and Microsoft.AspNetCore.NodeServices used to automatically create a console logger when logging isn't configured.

New behavior

Microsoft.AspNetCore.SpaServices and Microsoft.AspNetCore.NodeServices won't display console logs unless logging is configured.

Reason for change

There's a need to align with how other ASP.NET Core packages implement logging.

If the old behavior is required, to configure console logging, add services.AddLogging(builder => builder.AddConsole()) to your Setup.ConfigureServices method.

Category

ASP.NET Core

Affected APIs

None

Target framework: .NET Framework support dropped

Starting with ASP.NET Core 3.0, .NET Framework is an unsupported target framework.

Change description

.NET Framework 4.8 is the last major version of .NET Framework. New ASP.NET Core apps should be built on .NET Core. Starting with the .NET Core 3.0 release, you can think of ASP.NET Core 3.0 as being part of .NET Core.

Customers using ASP.NET Core with .NET Framework can continue in a fully supported fashion using the 2.1 LTS release. Support and servicing for 2.1 continues until at least August 21, 2021. This date is three years after declaration of the LTS release per the .NET Support Policy. Support for ASP.NET Core 2.1 packages on .NET Framework will extend indefinitely, similar to the servicing policy for other package-based ASP.NET frameworks.

For more information about porting from .NET Framework to .NET Core, see Porting to .NET Core.

Microsoft.Extensions packages (such as logging, dependency injection, and configuration) and Entity Framework Core aren't affected. They'll continue to support .NET Standard.

For more information on the motivation for this change, see the original blog post.

Version introduced

3.0

Old behavior

ASP.NET Core apps could run on either .NET Core or .NET Framework.

New behavior

ASP.NET Core apps can only be run on .NET Core.

Take one of the following actions:

  • Keep your app on ASP.NET Core 2.1.
  • Migrate your app and dependencies to .NET Core.

Category

ASP.NET Core

Affected APIs

None