TaskCanceled Exception thrown from Microsoft.AspNetCore.Authentication.JwtBearer.JwtBearerHandler class

Dear all,

We have a .NET Core Web API service which makes use of the Authentication middleware readily available with .NET 5.0. In our service we have registered 4 different jwt bearer authentication schemes on startup of the service, (why? - that's because we are in the process of migrating from two older identity providers to two newer ones. For example, we are migrating from Azure AD V1 auth endpoints to the Microsoft Identity Platform (V2)).

In a number of our deployments we see TaskCanceled exceptions with the below stack trace, when certain api's are called. The api's are all protected by an [Authorize] attribute which makes use of the aforementioned auth schemes that are registered at startup

Details of the service:
SDK version: .NET 5.0.401
Base docker image: mcr.microsoft.com/dotnet/aspnet:5.0.10

We always seem to have 2 of these exceptions thrown simultaeneously:

```
System.Threading.Tasks.TaskCanceledException:
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.IdentityModel.Protocols.ConfigurationManager`1+d__24.MoveNext (Microsoft.IdentityModel.Protocols, Version=6.7.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authentication.JwtBearer.JwtBearerHandler+d__6.MoveNext (Microsoft.AspNetCore.Authentication.JwtBearer, Version=5.0.10.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authentication.JwtBearer.JwtBearerHandler+d__6.MoveNext (Microsoft.AspNetCore.Authentication.JwtBearer, Version=5.0.10.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authentication.AuthenticationHandler`1+d__48.MoveNext (Microsoft.AspNetCore.Authentication, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authentication.AuthenticationService+d__14.MoveNext (Microsoft.AspNetCore.Authentication.Core, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authorization.Policy.PolicyEvaluator+d__2.MoveNext (Microsoft.AspNetCore.Authorization.Policy, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware+d__6.MoveNext (Microsoft.AspNetCore.Authorization.Policy, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware+d__6.MoveNext (Microsoft.AspNetCore.Authentication, Version=5.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Startup+<>c+<b__9_0>d.MoveNext
```

And the second exception stack trace:

```
System.Threading.Tasks.TaskCanceledException:
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.IdentityModel.Protocols.ConfigurationManager`1+d__24.MoveNext (Microsoft.IdentityModel.Protocols, Version=6.7.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.AspNetCore.Authentication.JwtBearer.JwtBearerHandler+d__6.MoveNext (Microsoft.AspNetCore.Authentication.JwtBearer, Version=5.0.10.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
```

The troublesome thing is that I can't seem to reproduce this error intentionally. We set up suitable load tests to test the affected api's, but we don't seem to be able to reproduce the failures as part of the load tests, but the errors keep happening in the same environments. As far as I can tell we have configured the middleware correctly as for the majority of our calls we are able to authenticate and authorize correctly (we have automated tests testing various scenarios).

But in certain sporadic cases, we get these exceptions.