NullReferenceException

[GF-Huang]

-------------------------------------------------------------------
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info: Microsoft.Hosting.Lifetime[0]
      Now listening on: http://[::]:80
Microsoft.Hosting.Lifetime: Information: Now listening on: http://[::]:80
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
Microsoft.Hosting.Lifetime: Information: Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
Microsoft.Hosting.Lifetime: Information: Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /app
Microsoft.Hosting.Lifetime: Information: Content root path: /app
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
System.AggregateException: One or more errors occurred. (One or more errors occurred. (Object reference not set to an instance of an object.))
 ---> System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at VueCliMiddleware.PidUtils.GetPortPid(UInt16 port)
   at VueCliMiddleware.PidUtils.KillPort(UInt16 port, Boolean force, Boolean tree)
   at VueCliMiddleware.VueCliMiddleware.StartVueCliServerAsync(String sourcePath, String npmScriptName, ILogger logger, Int32 portNumber, ScriptRunnerType runner, String regex)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.VueCliMiddleware.<>c.<Attach>b__3_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.TaskTimeoutExtensions.WithTimeout[T](Task`1 task, TimeSpan timeoutDelay, String message)
   at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task`1 baseUriTask, CancellationToken applicationStoppingToken, Boolean proxy404s)
   at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.<>c__DisplayClass2_0.<<UseProxyToSpaDevelopmentServer>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

System.AggregateException: One or more errors occurred. (One or more errors occurred. (Object reference not set to an instance of an object.))
 ---> System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at VueCliMiddleware.PidUtils.GetPortPid(UInt16 port)
   at VueCliMiddleware.PidUtils.KillPort(UInt16 port, Boolean force, Boolean tree)
   at VueCliMiddleware.VueCliMiddleware.StartVueCliServerAsync(String sourcePath, String npmScriptName, ILogger logger, Int32 portNumber, ScriptRunnerType runner, String regex)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.VueCliMiddleware.<>c.<Attach>b__3_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.TaskTimeoutExtensions.WithTimeout[T](Task`1 task, TimeSpan timeoutDelay, String message)
   at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task`1 baseUriTask, CancellationToken applicationStoppingToken, Boolean proxy404s)
   at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.<>c__DisplayClass2_0.<<UseProxyToSpaDevelopmentServer>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
System.AggregateException: One or more errors occurred. (One or more errors occurred. (Object reference not set to an instance of an object.))
 ---> System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at VueCliMiddleware.PidUtils.GetPortPid(UInt16 port)
   at VueCliMiddleware.PidUtils.KillPort(UInt16 port, Boolean force, Boolean tree)
   at VueCliMiddleware.VueCliMiddleware.StartVueCliServerAsync(String sourcePath, String npmScriptName, ILogger logger, Int32 portNumber, ScriptRunnerType runner, String regex)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.VueCliMiddleware.<>c.<Attach>b__3_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.TaskTimeoutExtensions.WithTimeout[T](Task`1 task, TimeSpan timeoutDelay, String message)
   at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task`1 baseUriTask, CancellationToken applicationStoppingToken, Boolean proxy404s)
   at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.<>c__DisplayClass2_0.<<UseProxyToSpaDevelopmentServer>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

System.AggregateException: One or more errors occurred. (One or more errors occurred. (Object reference not set to an instance of an object.))
 ---> System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at VueCliMiddleware.PidUtils.GetPortPid(UInt16 port)
   at VueCliMiddleware.PidUtils.KillPort(UInt16 port, Boolean force, Boolean tree)
   at VueCliMiddleware.VueCliMiddleware.StartVueCliServerAsync(String sourcePath, String npmScriptName, ILogger logger, Int32 portNumber, ScriptRunnerType runner, String regex)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.VueCliMiddleware.<>c.<Attach>b__3_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.TaskTimeoutExtensions.WithTimeout[T](Task`1 task, TimeSpan timeoutDelay, String message)
   at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task`1 baseUriTask, CancellationToken applicationStoppingToken, Boolean proxy404s)
   at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.<>c__DisplayClass2_0.<<UseProxyToSpaDevelopmentServer>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
System.AggregateException: One or more errors occurred. (One or more errors occurred. (Object reference not set to an instance of an object.))
 ---> System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at VueCliMiddleware.PidUtils.GetPortPid(UInt16 port)
   at VueCliMiddleware.PidUtils.KillPort(UInt16 port, Boolean force, Boolean tree)
   at VueCliMiddleware.VueCliMiddleware.StartVueCliServerAsync(String sourcePath, String npmScriptName, ILogger logger, Int32 portNumber, ScriptRunnerType runner, String regex)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.VueCliMiddleware.<>c.<Attach>b__3_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.TaskTimeoutExtensions.WithTimeout[T](Task`1 task, TimeSpan timeoutDelay, String message)
   at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task`1 baseUriTask, CancellationToken applicationStoppingToken, Boolean proxy404s)
   at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.<>c__DisplayClass2_0.<<UseProxyToSpaDevelopmentServer>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware: Error: An unhandled exception has occurred while executing the request.

System.AggregateException: One or more errors occurred. (One or more errors occurred. (Object reference not set to an instance of an object.))
 ---> System.AggregateException: One or more errors occurred. (Object reference not set to an instance of an object.)
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at VueCliMiddleware.PidUtils.GetPortPid(UInt16 port)
   at VueCliMiddleware.PidUtils.KillPort(UInt16 port, Boolean force, Boolean tree)
   at VueCliMiddleware.VueCliMiddleware.StartVueCliServerAsync(String sourcePath, String npmScriptName, ILogger logger, Int32 portNumber, ScriptRunnerType runner, String regex)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.VueCliMiddleware.<>c.<Attach>b__3_0(Task`1 task)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at VueCliMiddleware.TaskTimeoutExtensions.WithTimeout[T](Task`1 task, TimeSpan timeoutDelay, String message)
   at Microsoft.AspNetCore.SpaServices.Extensions.Proxy.SpaProxy.PerformProxyRequest(HttpContext context, HttpClient httpClient, Task`1 baseUriTask, CancellationToken applicationStoppingToken, Boolean proxy404s)
   at Microsoft.AspNetCore.Builder.SpaProxyingExtensions.<>c__DisplayClass2_0.<<UseProxyToSpaDevelopmentServer>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

[EEParker]

Can you try running visual studio as administrator?

[GF-Huang]

Can you try running visual studio as administrator?

Same result.

[drpeck]

I had this issue. It was resolved when I didn't run my app through a Docker container, though so far I've been unable to determine why.

[Kingside88]

Please post us you're piece of code from startup.cs which implements VueCliMiddleware.
Does you're App running with npm? (npm run serve)

[Popeye4242]

Can confirm that this happens when you run this in a docker container.

Reproduction:

• Create a project with vueclimiddleware - You could use this for fast setup: https://marketplace.visualstudio.com/items?itemName=alexandredotnet.vuejsdotnetfive
• Right click the created project > Add > Docker Support
• Change the run configuration from IIS Express to Docker