System.ArgumentNullException during debugging via Visual Studio

[gabesmsft]

I understand that the Visual Studio debugging experience is still being worked on, but I want to report this issue in case it isn't a known issue. The following issue happens even when I uncomment the Debugger.Launch() statement. The same project works as expected when starting from command line or VS Code.

Am using the sample code provided in this GitHub repo, as-is. Am hitting a System.ArgumentNullException during host startup issue that only happens in Visual Studio when running the following part of the sample code: https://github.com/Azure/azure-functions-dotnet-worker-preview/blob/main/FunctionApp/Program.cs#L22-L25

This issue can be consistently reproduced even on a fresh new Windows machine with the following software installed: Visual Studio 2019: version 16.8.3 Microsoft.NET SDK 5.0.100 x64 Azure Functions Core Tools 3.0.3160 (x64)

Here is the full stack trace of the exception: System.ArgumentNullException HResult=0x80004003 Message=Value cannot be null. (Parameter 'value') Source=Google.Protobuf StackTrace: at Google.Protobuf.ProtoPreconditions.CheckNotNull[T](T value, String name) at Microsoft.Azure.WebJobs.Script.Grpc.Messages.StartStream.set_WorkerId(String value) in D:\a\1\s\src\DotNetWorker\obj\Release\net5.0\FunctionRpc.cs:line 1414 at Microsoft.Azure.Functions.Worker.WorkerHostedService.d9.MoveNext() in D:\a\1\s\src\DotNetWorker\WorkerHostedService.cs:line 48 at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter.GetResult() at Microsoft.Azure.Functions.Worker.WorkerHostedService.d7.MoveNext() in D:\a\1\s\src\DotNetWorker\WorkerHostedService.cs:line 37 at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at Microsoft.Extensions.Hosting.Internal.Host.d9.MoveNext() at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter.GetResult() at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.d4.MoveNext() at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.Extensions.Hosting.HostingAbstractionsHostExtensions.d4.MoveNext() at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter.GetResult() at FunctionApp.Program.

d0.MoveNext() in C:\temp\FunctionsNet5\FunctionApp\Program.cs:line 32

[Spaceman1861]

I fixed this issue by changing this

var host = new HostBuilder()
  .ConfigureAppConfiguration(c => {})
  .ConfigureFunctionsWorker((c, b) =>
  {
    b.UseFunctionExecutionMiddleware();
  })
  .Build();

To this

var host = new HostBuilder()
  .ConfigureAppConfiguration(c => {
    c.AddCommandLine(args);
  })
  .ConfigureFunctionsWorker((c, b) =>
  {
     b.UseFunctionExecutionMiddleware();
  })
  .Build();

Didnt really dig into why, hope it helps

[gabesmsft]

I am already using the ConfigureAppConfiguration(c =>{c.AddCommandLine(args);}) lines (it was already part of this github repo when I downloaded the code), but am hitting the described issue in Visual Studio all the same, but thanks for your reply.

[synercoder]

I have this same issue, first I created a new project and followed the readme. Then I started hitting this issue. So I thought perhaps I did something wrong, cloned the project, tried to launch that as well and....

The "fix" mentioned by @Spaceman1861 did not work for me, no matter what combo of configure I did or didn't use.

Edit with version infos:

Using Core Tools Version: 3.0.3160 Commit hash: 00aa7f43cc5c5f15241b5e6e5363256f19ceb990 Visual Studio 16.8.3 & Tried Visual Studio 16.9.0 Preview 2.0

And my dotnet --info says:

.NET SDK (reflecting any global.json):
 Version:   5.0.200-preview.20601.7
 Commit:    b3b934bbf2

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19042
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.200-preview.20601.7\

Host (useful for support):
  Version: 5.0.1
  Commit:  b02e13abab

.NET SDKs installed:
  2.1.509 [C:\Program Files\dotnet\sdk]
  2.1.802 [C:\Program Files\dotnet\sdk]
  2.2.402 [C:\Program Files\dotnet\sdk]
  5.0.101 [C:\Program Files\dotnet\sdk]
  5.0.200-preview.20601.7 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.9 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[synercoder]

Solved:

You can not debug the application directly using Visual Studio.

You can only start by using the command line func host start. If you do not, Visual Studio will try to debug the application directly instead of serving it using an out-of-process host that starts it.

I think this issue can be closed as @gabesmsft and me not understanding / reading the readme good enough.