Descriptive Error for Improper Use of [AsParameters] with IFormFileCollection in .NET 8 Minimal APIs

[HaikAsatryan]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Problem Description

In .NET 8 minimal APIs, when using the [AsParameters] attribute on an IFormFileCollection parameter, the resulting error message is extremely long and non-descriptive. This can make it difficult for developers to diagnose the issue.

Example Code

The following endpoint works correctly:

app.MapPost("/correct", (IFormFileCollection files) => TypedResults.Ok());

However, if a developer mistakenly uses [AsParameters] like this:

app.MapPost("/incorrect", ([AsParameters] IFormFileCollection files) => TypedResults.Ok());
app.MapPost("/incorrect", ([AsParameters] List<IFormFile> files) => TypedResults.Ok());

The error message returned by ASP.NET Core is long and unclear.

Actual Error Message
It is too long so I cannot copy paste it here but I left extract from it in the exception message place.

Expected Behavior

ASP.NET Core should provide a more descriptive and concise error message that clearly indicates the misuse of [AsParameters] with IFormFileCollection. For example, it should state that [AsParameters] is not supported with IFormFileCollection.

Steps To Reproduce

No response

Exceptions (if any)

Actual Error Message

System.OperationCanceledException: The operation was canceled.
   at System.Threading.PeriodicTimer.State.Signal(Boolean stopping, CancellationToken cancellationToken)
   at System.Threading.CancellationTokenSource.Invoke(Delegate d, Object state, CancellationTokenSource source)
   at System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.<DisposeAsync>g__Await|26_0(Int32 i, ValueTask vt, List`1 toDispose)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder.SetResult()
   at MassTransit.MassTransitHostedService.DisposeAsync() in /_/src/MassTransit/MassTransitHostedService.cs:line 40
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task.TrySetResult()
   at System.Threading.Tasks.Task.WhenAllPromise.Invoke(Task completedTask)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.MassTransitBus.StopAsync(CancellationToken cancellationToken) in /_/src/MassTransit/MassTransitBus.cs:line 268
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.MassTransitBus.Handle.StopAsync(CancellationToken cancellationToken) in /_/src/MassTransit/MassTransitBus.cs:line 411
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Transports.BaseHost.Stop(CancellationToken cancellationToken) in /_/src/MassTransit/Transports/BaseHost.cs:line 160
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Middleware.Agent.Stop(StopContext context) in /_/src/MassTransit.Abstractions/Middleware/Middleware/Agent.cs:line 93
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Transports.TransportPipeContextSupervisor`1.StopSupervisor(StopSupervisorContext context) in /_/src/MassTransit/Transports/TransportPipeContextSupervisor.cs:line 46
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Agents.PipeContextSupervisor`1.StopSupervisor(StopSupervisorContext context) in /_/src/MassTransit/Agents/PipeContextSupervisor.cs:line 90
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecuteFromThreadPool(Thread threadPoolThread)
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()
--- End of stack trace from previous location ---
   at System.Threading.PeriodicTimer.State.System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult(Int16 token)
   at MassTransit.PostgresOutbox.Jobs.InboxMessageRemovalService`1.ExecuteAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.Internal.Host.TryExecuteBackgroundServiceAsync(BackgroundService backgroundService)
[11:06:56 FTL] The HostOptions.BackgroundServiceExceptionBehavior is configured to StopHost. A BackgroundService has thrown an unhandled exception, and the IHost instance is stopping. To avoid this behavior, configure this to Ignore; however the BackgroundService will not be restarted.
System.OperationCanceledException: The operation was canceled.
   at System.Threading.PeriodicTimer.State.Signal(Boolean stopping, CancellationToken cancellationToken)
   at System.Threading.CancellationTokenSource.Invoke(Delegate d, Object state, CancellationTokenSource source)
   at System.Threading.CancellationTokenSource.ExecuteCallbackHandlers(Boolean throwOnFirstException)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.<DisposeAsync>g__Await|26_0(Int32 i, ValueTask vt, List`1 toDispose)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncValueTaskMethodBuilder.SetResult()
   at MassTransit.MassTransitHostedService.DisposeAsync() in /_/src/MassTransit/MassTransitHostedService.cs:line 40
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task.TrySetResult()
   at System.Threading.Tasks.Task.WhenAllPromise.Invoke(Task completedTask)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.MassTransitBus.StopAsync(CancellationToken cancellationToken) in /_/src/MassTransit/MassTransitBus.cs:line 268
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.MassTransitBus.Handle.StopAsync(CancellationToken cancellationToken) in /_/src/MassTransit/MassTransitBus.cs:line 411
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Transports.BaseHost.Stop(CancellationToken cancellationToken) in /_/src/MassTransit/Transports/BaseHost.cs:line 160
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Middleware.Agent.Stop(StopContext context) in /_/src/MassTransit.Abstractions/Middleware/Middleware/Agent.cs:line 93
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Transports.TransportPipeContextSupervisor`1.StopSupervisor(StopSupervisorContext context) in /_/src/MassTransit/Transports/TransportPipeContextSupervisor.cs:line 46
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext()
   at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
   at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
   at System.Threading.Tasks.Task`1.TrySetResult(TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.SetExistingTaskResult(Task`1 task, TResult result)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder.SetResult()
   at MassTransit.Agents.PipeContextSupervisor`1.StopSupervisor(StopSupervisorContext context) in /_/src/MassTransit/Agents/PipeContextSupervisor.cs:line 90
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecutionContextCallback(Object s)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.MoveNext(Thread threadPoolThread)
   at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.AsyncStateMachineBox`1.ExecuteFromThreadPool(Thread threadPoolThread)
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()
--- End of stack trace from previous location ---
   at System.Threading.PeriodicTimer.State.System.Threading.Tasks.Sources.IValueTaskSource<System.Boolean>.GetResult(Int16 token)
   at MassTransit.PostgresOutbox.Jobs.InboxMessageRemovalService`1.ExecuteAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.Internal.Host.TryExecuteBackgroundServiceAsync(BackgroundService backgroundService)
[11:06:56 INF] Application is shutting down...
[11:06:56 ERR] BackgroundService failed

.NET Version

8.0.2

Anything else?

No response

[martincostello]

The stack trace here doesn't seem to be anything to do with Minimal APIs - it's to do with MassTransit. What exception do you get if you temporarily remove your background service? It could be that one problem is causing another, but then that problem masks the original error, meaning it looks like you get a terrible error message.

[HaikAsatryan]

To clarify, the error message is indeed a result of using the [AsParameters] attribute incorrectly. The issue isn't related to MassTransit or other dependencies, as we encountered this problem in a nearly empty project as well.

The error message generated is over 300K characters, making it impractical to post in full here. It encompasses details from various components of our project, including MassTransit, Hangfire, MediatR, etc., leading to a convoluted stack trace.

Here’s an example in a minimal setup:

Reproducible Example:

app.MapPost("err", ([AsParameters]List<IFormFile> files) => "OK");

Resulting Error:

crit: Microsoft.AspNetCore.Hosting.Diagnostics[6]
      Application startup exception
      System.InvalidProgramException: Common Language Runtime detected an invalid program.
         at System.Reflection.Emit.DynamicMethod.CreateDelegate(Type delegateType, Object target)
         at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda)
         at System.Linq.Expressions.Expression`1.Compile()
         at Microsoft.AspNetCore.Http.RequestDelegateFactory.HandleRequestBodyAndCompileRequestDelegateForForm(Expression responseWritingMethodCall, RequestDelegateFactoryContext factoryContext)
         at Microsoft.AspNetCore.Http.RequestDelegateFactory.Create(Delegate handler, RequestDelegateFactoryOptions options, RequestDelegateMetadataResult metadataResult)
         at Microsoft.AspNetCore.Routing.RouteEndpointDataSource.CreateRouteEndpointBuilder(RouteEntry entry, RoutePattern groupPrefix, IReadOnlyList`1 groupConventions, IReadOnlyList`1 groupFinallyConventions)
         at Microsoft.AspNetCore.Routing.RouteEndpointDataSource.get_Endpoints()
         at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.CreateEndpointsUnsynchronized()
         at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.EnsureEndpointsInitialized()
         at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.get_Endpoints()
         at Microsoft.AspNetCore.Routing.DataSourceDependentCache`1.Initialize()
         at System.Threading.LazyInitializer.EnsureInitializedCore[T](T& target, Boolean& initialized, Object& syncLock, Func`1 valueFactory)
         at Microsoft.AspNetCore.Routing.DataSourceDependentCache`1.EnsureInitialized()
         at Microsoft.AspNetCore.Authorization.Policy.AuthorizationPolicyCache..ctor(EndpointDataSource dataSource)
         at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
         at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
         at System.Reflection.MethodBaseInvoker.InvokeWithOneArg(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite callSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
         at Microsoft.Extensions.DependencyInjection.ServiceProvider.CreateServiceAccessor(ServiceIdentifier serviceIdentifier)
         at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
         at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(ServiceIdentifier serviceIdentifier, ServiceProviderEngineScope serviceProviderEngineScope)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
         at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware..ctor(RequestDelegate next, IAuthorizationPolicyProvider policyProvider, IServiceProvider services)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddlewareInternal..ctor(RequestDelegate next, IServiceProvider services, IAuthorizationPolicyProvider policyProvider, ILogger`1 logger)
         at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
         at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
         at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at Microsoft.Extensions.Internal.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider)
         at Microsoft.Extensions.Internal.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters)
         at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.ReflectionMiddlewareBinder.CreateMiddleware(RequestDelegate next)
         at Microsoft.AspNetCore.Builder.ApplicationBuilder.Build()
         at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
fail: Microsoft.Extensions.Hosting.Internal.Host[11]
      Hosting failed to start
      System.InvalidProgramException: Common Language Runtime detected an invalid program.
         at System.Reflection.Emit.DynamicMethod.CreateDelegate(Type delegateType, Object target)
         at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda)
         at System.Linq.Expressions.Expression`1.Compile()
         at Microsoft.AspNetCore.Http.RequestDelegateFactory.HandleRequestBodyAndCompileRequestDelegateForForm(Expression responseWritingMethodCall, RequestDelegateFactoryContext factoryContext)
         at Microsoft.AspNetCore.Http.RequestDelegateFactory.Create(Delegate handler, RequestDelegateFactoryOptions options, RequestDelegateMetadataResult metadataResult)
         at Microsoft.AspNetCore.Routing.RouteEndpointDataSource.CreateRouteEndpointBuilder(RouteEntry entry, RoutePattern groupPrefix, IReadOnlyList`1 groupConventions, IReadOnlyList`1 groupFinallyConventions)
         at Microsoft.AspNetCore.Routing.RouteEndpointDataSource.get_Endpoints()
         at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.CreateEndpointsUnsynchronized()
         at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.EnsureEndpointsInitialized()
         at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.get_Endpoints()
         at Microsoft.AspNetCore.Routing.DataSourceDependentCache`1.Initialize()
         at System.Threading.LazyInitializer.EnsureInitializedCore[T](T& target, Boolean& initialized, Object& syncLock, Func`1 valueFactory)
         at Microsoft.AspNetCore.Routing.DataSourceDependentCache`1.EnsureInitialized()
         at Microsoft.AspNetCore.Authorization.Policy.AuthorizationPolicyCache..ctor(EndpointDataSource dataSource)
         at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
         at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
         at System.Reflection.MethodBaseInvoker.InvokeWithOneArg(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite callSite, RuntimeResolverContext context)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
         at Microsoft.Extensions.DependencyInjection.ServiceProvider.CreateServiceAccessor(ServiceIdentifier serviceIdentifier)
         at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
         at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(ServiceIdentifier serviceIdentifier, ServiceProviderEngineScope serviceProviderEngineScope)
         at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
         at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware..ctor(RequestDelegate next, IAuthorizationPolicyProvider policyProvider, IServiceProvider services)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddlewareInternal..ctor(RequestDelegate next, IServiceProvider services, IAuthorizationPolicyProvider policyProvider, ILogger`1 logger)
         at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
         at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
         at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
         at Microsoft.Extensions.Internal.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider)
         at Microsoft.Extensions.Internal.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters)
         at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.ReflectionMiddlewareBinder.CreateMiddleware(RequestDelegate next)
         at Microsoft.AspNetCore.Builder.ApplicationBuilder.Build()
         at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
         at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>b__15_1(IHostedService service, CancellationToken token)
         at Microsoft.Extensions.Hosting.Internal.Host.ForeachService[T](IEnumerable`1 services, CancellationToken token, Boolean concurrent, Boolean abortOnFirstException, List`1 exceptions, Func`3 operation)
Unhandled exception. System.InvalidProgramException: Common Language Runtime detected an invalid program.
   at System.Reflection.Emit.DynamicMethod.CreateDelegate(Type delegateType, Object target)
   at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda)
   at System.Linq.Expressions.Expression`1.Compile()
   at Microsoft.AspNetCore.Http.RequestDelegateFactory.HandleRequestBodyAndCompileRequestDelegateForForm(Expression responseWritingMethodCall, RequestDelegateFactoryContext factoryContext)
   at Microsoft.AspNetCore.Http.RequestDelegateFactory.Create(Delegate handler, RequestDelegateFactoryOptions options, RequestDelegateMetadataResult metadataResult)
   at Microsoft.AspNetCore.Routing.RouteEndpointDataSource.CreateRouteEndpointBuilder(RouteEntry entry, RoutePattern groupPrefix, IReadOnlyList`1 groupConventions, IReadOnlyList`1 groupFinallyConventions)
   at Microsoft.AspNetCore.Routing.RouteEndpointDataSource.get_Endpoints()
   at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.CreateEndpointsUnsynchronized()
   at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.EnsureEndpointsInitialized()
   at Microsoft.AspNetCore.Routing.CompositeEndpointDataSource.get_Endpoints()
   at Microsoft.AspNetCore.Routing.DataSourceDependentCache`1.Initialize()
   at System.Threading.LazyInitializer.EnsureInitializedCore[T](T& target, Boolean& initialized, Object& syncLock, Func`1 valueFactory)
   at Microsoft.AspNetCore.Routing.DataSourceDependentCache`1.EnsureInitialized()
   at Microsoft.AspNetCore.Authorization.Policy.AuthorizationPolicyCache..ctor(EndpointDataSource dataSource)
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
   at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
   at System.Reflection.MethodBaseInvoker.InvokeWithOneArg(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite callSite, RuntimeResolverContext context)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(ServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.Resolve(ServiceCallSite callSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.CreateServiceAccessor(ServiceIdentifier serviceIdentifier)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(ServiceIdentifier serviceIdentifier, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware..ctor(RequestDelegate next, IAuthorizationPolicyProvider policyProvider, IServiceProvider services)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddlewareInternal..ctor(RequestDelegate next, IServiceProvider services, IAuthorizationPolicyProvider policyProvider, ILogger`1 logger)
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
   at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
   at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Reflection.RuntimeConstructorInfo.Invoke(BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Microsoft.Extensions.Internal.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider)
   at Microsoft.Extensions.Internal.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.ReflectionMiddlewareBinder.CreateMiddleware(RequestDelegate next)
   at Microsoft.AspNetCore.Builder.ApplicationBuilder.Build()
   at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>b__15_1(IHostedService service, CancellationToken token)
   at Microsoft.Extensions.Hosting.Internal.Host.ForeachService[T](IEnumerable`1 services, CancellationToken token, Boolean concurrent, Boolean abortOnFirstException, List`1 exceptions, Func`3 operation)
   at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.RunAsync(IHost host, CancellationToken token)
   at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.Run(IHost host)
   at Program.<Main>$(String[] args) in C:\Users\HIDEDPATH\Program.cs:line 35

We have spent more than an hour until we have found the error in our case.

[martincostello]

Thanks - that looks like it contains enough information now for someone to look into.

[captainsafia]

I believe the root cause of the issue in both of these cases is the fact that parameter annotated with the AsParameters attribute consists of an interface type that we can't instantiate when we bind to the complex type.

I see two different strategies for solving this:

• Provide an analyzer to warn about this pattern.
• Add a set of runtime checks as we construct the parameter binding logic if we encounter [AsParameters] in an unsupported type.

The first approach has the benefit of "shifting left" the error and alerting users earlier in the dev loop that their handler is invalid. The second approach won't warn users until they send the first request to the app but is easier to roll out.

I'm putting this in the backlog for now although I'm happy to review a PR or provide pointers as to how we can go about fixing it.