Why is IIS not able to access the web.config file

Nils Bezjak 20

Hello,

I recently hosted a web app via Azure App Service and GitHub Actions in Azure. After sending a request to the app service, I got a huge error message in the log stream, which had the following description somewhere inside:

<h3>HTTP Error 500.0 - Internal Server Error</h3><h4>The page cannot be displayed because an internal server error has occurred.</h4></div><div class="content-container"><fieldset><h4>Most likely causes:</h4><ul> <li>IIS received the request; however, an internal error occurred during the processing of the request. The root cause of this error depends on which module handles the request and what was happening in the worker process when this error occurred.</li> <li>IIS was not able to access the web.config file for the Web site or application. This can occur if the NTFS permissions are set incorrectly.</li> <li>IIS was not able to process configuration for the Web site or application.</li> <li>The authenticated user does not have permission to use this DLL.</li> <li>The request is mapped to a managed handler but the .NET Extensibility Feature is not installed.</li> </ul></fieldset></div><div class="content-container"><fieldset><h4>Things you can try:</h4><ul> <li>Ensure that the NTFS permissions for the web.config file are correct and allow access to the Web server's machine account.</li> <li>Check the event logs to see if any additional information was logged.</li> <li>Verify the permissions for the DLL.</li> <li>Install the .NET Extensibility feature if the request is mapped to a managed handler.</li> <li>Create a tracing rule to track failed requests for this HTTP status code. For more information about creating a tracing rule for failed requests, click <a href="http://go.microsoft.com/fwlink/?LinkID=66439">here</a>. </li> </ul></fieldset></div><div class="content-container"><fieldset><h4>Detailed Error Information:</h4><div id="details-left"><table border="0" cellpadding="0" cellspacing="0"><tr class="alt"><th>Module</th><td>&nbsp;&nbsp;&nbsp;AspNetCoreModuleV2</td></tr><tr><th>Notification</th><td>&nbsp;&nbsp;&nbsp;ExecuteRequestHandler</td></tr><tr class="alt"><th>Handler</th><td>&nbsp;&nbsp;&nbsp;aspNetCore</td></tr><tr><th>Error Code</th><td>&nbsp;&nbsp;&nbsp;0x00000000</td></tr></table></div><div id="details-right"><table border="0" cellpadding="0" cellspacing="0"><tr class="alt"><th>Requested URL</th><td>&nbsp;&nbsp;&nbsp;https://kvUpdateManager:80/api/product</td></tr><tr><th>Physical Path</th><td>&nbsp;&nbsp;&nbsp;C:\home\site\wwwroot\api\product</td></tr><tr class="alt"><th>Logon Method</th><td>&nbsp;&nbsp;&nbsp;Anonymous</td></tr><tr><th>Logon User</th><td>&nbsp;&nbsp;&nbsp;Anonymous</td></tr></table><div class="clear"></div></div></fieldset></div><div class="content-container"><fieldset><h4>More Information:</h4>This error means that there was a problem while processing the request. The request was received by the Web server, but during processing a fatal error occurred, causing the 500 error.<p><a href="http://go.microsoft.com/fwlink/?LinkID=62293&amp;IIS70Error=500,0,0x00000000,14393">View more information &raquo;</a></p><p>Microsoft Knowledge Base Articles:</p></fieldset>

Followed by a stack trace. I tried to look for answers for the past 3 days, but I couldn't find anything. I recreated the app and chatted with our DevOps engineer, but we haven't found anything. Hopefully someone can help. If you need any information, ask away.

I'm using net8.0

JasonPan - MSFT 5,456 Reputation points Microsoft Vendor

2024-09-05T13:20:44.1433333+00:00

Hi @Nils Bezjak,

Please find Development tools/Advanced Tools in your azure portal. And open the kudu site. Then check if the web.config was generated or not first.

Best Regards

Jason

Nils Bezjak 20

Hi @JasonPan - MSFT
I checked and the file is generated with the following contet:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <location path="." inheritInChildApplications="false">
    <system.webServer>
      <handlers>
        <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
      </handlers>
      <aspNetCore processPath="dotnet" arguments=".\appName.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" hostingModel="inprocess" />
    </system.webServer>
  </location>
</configuration>

JasonPan - MSFT 5,456 Reputation points Microsoft Vendor

2024-09-05T13:48:29.67+00:00

Hi @Nils Bezjak,

Try to set stdoutLogEnabled="true" and check the logs, you also can share with us, please don't forget to hide your sensitive information.

And the next steps are checking the Application Event Logs and Failed Request Tracing Logs.

Best Regards

Jason

Nils Bezjak 20

Hi @JasonPan - MSFT

the log file contains the following log 20240905.log

The Failed Request Traicing logs contain: https___appname_80_api_product, STATUS_CODE 500, 14375 ms, GET.xml

And the application Event Logs show the following:


Category: Microsoft.AspNetCore.Server.IIS.Core.IISHttpServer
EventId: 2
SpanId: d63d8a564097fef9
TraceId: 52fad94e928cff0faa4bfa7b408db6ba
ParentId: 0000000000000000
RequestId: 8000640b-0000-ec00-b63f-84710c7967bb
RequestPath: /api/product

Connection ID "17005592194561631241", Request ID "8000640b-0000-ec00-b63f-84710c7967bb": An unhandled exception was thrown by the application.

Exception: 
System.InvalidOperationException: The ConnectionString property has not been initialized.
   at Microsoft.Data.SqlClient.SqlConnection.PermissionDemand()
   at Microsoft.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry, SqlConnectionOverrides overrides)
   at Microsoft.Data.SqlClient.SqlConnection.InternalOpenAsync(CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenAsync(CancellationToken cancellationToken, Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at code.cs:line 28
   at lambda_method13(Closure, Object)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.AwaitableObjectResultExecutor.Execute(ActionContext actionContext, IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Logged|12_1(ControllerActionInvoker invoker)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|7_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContextOfT`1.ProcessRequestAsync()

and

Category: Microsoft.EntityFrameworkCore.Query
EventId: 10100
SpanId: d63d8a564097fef9
TraceId: 52fad94e928cff0faa4bfa7b408db6ba
ParentId: 0000000000000000
RequestId: 8000640b-0000-ec00-b63f-84710c7967bb
RequestPath: /api/product
ActionId: fdc4303e-0840-4004-9b66-3ae7a09e871c

An exception occurred while iterating over the results of a query for context type 'KvUpdateManager.Models.ProductContext'.
System.InvalidOperationException: The ConnectionString property has not been initialized.
   at Microsoft.Data.SqlClient.SqlConnection.PermissionDemand()
   at Microsoft.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry, SqlConnectionOverrides overrides)
   at Microsoft.Data.SqlClient.SqlConnection.InternalOpenAsync(CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenAsync(CancellationToken cancellationToken, Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()

Exception: 
System.InvalidOperationException: The ConnectionString property has not been initialized.
   at Microsoft.Data.SqlClient.SqlConnection.PermissionDemand()
   at Microsoft.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry, SqlConnectionOverrides overrides)
   at Microsoft.Data.SqlClient.SqlConnection.InternalOpenAsync(CancellationToken cancellationToken)
--- End of stack trace from previous location ---
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenAsync(CancellationToken cancellationToken, Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()

JasonPan - MSFT 5,456 Reputation points Microsoft Vendor

2024-09-05T14:36:23.38+00:00
Hi @Nils Bezjak,

From the exception message,

An exception occurred while iterating over the results of a query for context type 'KvUpdateManager.Models.ProductContext'. System.InvalidOperationException: The ConnectionString property has not been initialized.

this is obviously a problem with the database connection string, please check whether the string in the appsettings.json file in the kudu site is correct.

Also check if Connection strings are also set in the azure portal, if so, this will overwrite the value in the appsettings.json.

Best Regards

Jason
JasonPan - MSFT 5,456 Reputation points Microsoft Vendor

2024-09-05T14:43:13.04+00:00

Hi @Nils Bezjak,

For this general exception, you can contact the Developer Team, they know how to troubleshoot/fix the issue.

You can also share more code with me, such as AddDbContext in the Program.cs. and the format of the configuration file in the appsettings.json (replacing important values with test_value) is also helpful.

Best Regards

Jason

Nils Bezjak 20

Hi @JasonPan - MSFT

I was able to solve the error. I was following a Microsoft tutorial, which resulted in some code which apparently didn't work. I did try to find the tutorial again, but I wasn't able to. I may try to find it later this day and post it as an answer if you want me to.

Code from tutorial:

if (builder.Environment.IsDevelopment())
{
    builder.Configuration.AddEnvironmentVariables().AddJsonFile("appsettings.Development.json");
    connection = builder.Configuration.GetConnectionString("AZURE_SQL");
}
else
{
    connection = Environment.GetEnvironmentVariable("AZURE_SQL"); }

Fix:

if (builder.Environment.IsDevelopment())
{
    builder.Configuration.AddEnvironmentVariables().AddJsonFile("appsettings.Development.json");
    connection = builder.Configuration.GetConnectionString("AZURE_SQL");
}
else
    connection = builder.Configuration.GetConnectionString("AZURE_SQL");

Now I can successfully request the data and the errors do not appear anymore.

Thank you very much for pointing me into the right direction.

Have a great weekend!

Best regards

Nils

Nils Bezjak 20

Hi @JasonPan - MSFT

I was able to fix the problem by changing the code from a Microsoft tutorial:

if (builder.Environment.IsDevelopment())
{
    builder.Configuration.AddEnvironmentVariables().AddJsonFile("appsettings.Development.json");
    connection = builder.Configuration.GetConnectionString("AZURE_SQL");
}
else
{
    connection = Environment.GetEnvironmentVariable("AZURE_SQL");
}

to:

if (builder.Environment.IsDevelopment())
{
    builder.Configuration.AddEnvironmentVariables().AddJsonFile("appsettings.Development.json");
    connection = builder.Configuration.GetConnectionString("AZURE_SQL");
}
else
    connection = builder.Configuration.GetConnectionString("AZURE_SQL");

I was not able to find the tutorial, but if you want me to, I can of course search again and try to find it.

Thank you very much for pointing me into the right direction.

Best regards

Nils

Accepted answer

JasonPan - MSFT 5,456 Reputation points Microsoft Vendor

2024-09-06T12:58:43.65+00:00
Hi @Nils Bezjak,

Reading the connection string in the asp.net core project is done using the following code.

builder.Configuration.GetConnectionString("AZURE_SQL");

Source Code

Suggestion
Since we are using Azure Web App, it is recommend to use connection string feature like below. Here is the official link: Configure connection strings.

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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Best regards,

Jason
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1 person found this answer helpful.
Nils Bezjak 20 Reputation points

2024-09-06T14:02:58.8633333+00:00

Hi @JasonPan - MSFT

it seems my previous comments have been automatically deleted, for some reason.
I also discovered that and the Microsoft tutorial I was following did suggest another way. I implemented the new code and the service now works.
Thank you very much.

Best regards,

Nils
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