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Migrate from ASP.NET Core in .NET 8 to ASP.NET Core in .NET 9

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This article explains how to update an ASP.NET Core in .NET 8 to ASP.NET Core in .NET 9.

Prerequisites

Update the .NET SDK version in global.json

If you rely on a global.json file to target a specific .NET Core SDK version, update the version property to the .NET 9.0 SDK version that's installed. For example:

{
  "sdk": {
-    "version": "8.0.100"
+    "version": "9.0.100"
  }
}

Update the target framework

Update the project file's Target Framework Moniker (TFM) to net9.0:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
  </PropertyGroup>

</Project>

Update package references

In the project file, update each Microsoft.AspNetCore.*, Microsoft.EntityFrameworkCore.*, Microsoft.Extensions.*, and System.Net.Http.Json package reference's Version attribute to 9.0.0 or later. For example:

<ItemGroup>
-   <PackageReference Include="Microsoft.AspNetCore.JsonPatch" Version="8.0.2" />
-   <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="8.0.2" />
-   <PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="8.0.0" />
-   <PackageReference Include="System.Net.Http.Json" Version="8.0.0" />
+   <PackageReference Include="Microsoft.AspNetCore.JsonPatch" Version="9.0.0-preview.1.24081.5" />
+   <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="9.0.0-preview.1.24081.2" />
+   <PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="9.0.0-preview.1.24080.9" />
+   <PackageReference Include="System.Net.Http.Json" Version="9.0.0-preview.1.24080.9" />
</ItemGroup>

Blazor

Blazor migration guidance will appear here prior to the release of .NET 9, which is scheduled for November, 2024.

Additional resources