Null Reference Exception

Sometimes I got this stack trace from event viewer. My application crashes and there is no way back. I also created a stackoverflow question for this.

Here is the stack trace from windows event viewer:

Application: X.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.NullReferenceException
   at SlackAPI.RequestState`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].GotResponse(System.IAsyncResult)
   at System.Net.LazyAsyncResult.Complete(IntPtr)
   at System.Net.ContextAwareResult.CompleteCallback(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
   at System.Net.ContextAwareResult.Complete(IntPtr)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(System.Object, IntPtr)
   at System.Net.HttpWebRequest.SetResponse(System.Exception)
   at System.Net.HttpWebRequest.SetAndOrProcessResponse(System.Object)
   at System.Net.ConnectionReturnResult.SetResponses(System.Net.ConnectionReturnResult)
   at System.Net.Connection.CompleteConnectionWrapper(System.Object, System.Object)
   at System.Net.PooledStream.ConnectionCallback(System.Object, System.Exception, System.Net.Sockets.Socket, System.Net.IPAddress)
   at System.Net.ServicePoint.ConnectSocketCallback(System.IAsyncResult)
   at System.Net.LazyAsyncResult.Complete(IntPtr)
   at System.Net.ContextAwareResult.Complete(IntPtr)
   at System.Net.LazyAsyncResult.ProtectedInvokeCallback(System.Object, IntPtr)
   at System.Net.Sockets.BaseOverlappedAsyncResult.CompletionPortCallback(UInt32, UInt32, System.Threading.NativeOverlapped*)
   at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32, UInt32, System.Threading.NativeOverlapped*)

Faulting application name: X.exe, version: 1.5.0.0, time stamp: 0x5914053a
Faulting module name: unknown, version: 0.0.0.0, time stamp: 0x00000000
Exception code: 0xc0000005
Fault offset: 0x0655a904
Faulting process id: 0x1bb0
Faulting application start time: 0x01d2ca214de3853b
Faulting application path: PATH-TO-X.exe
Faulting module path: unknown
Report Id: 5ef2a70f-387a-11e7-9c66-000c29bbc8ee

[Inumedia]

Could you try with 21bdc49 and see if it still happens?

Sure, But because it's production environment it may take a while.

[Inumedia]

No worries, my hunch is that a request is timing out and response is coming back as null. So if we don't get a response I'll just let the exception bubble up so it will give the proper exception type. As for handling it, I'm not super sure how to implement that yet and will likely need to be a much larger change.

Yeah, maybe. I use Slack API in an async method so I thought throwing an exception should make just a task become failed. But it takes down the entire application. By the way thank you for the API. It has been helped me a lot.

Yesterday the error happened again. Pulled and added the commit to the application. I will inform you of any further events.

Hi @Inumedia,
After 4 days there is no sign of old error. Thanks for the patch.

I got another kind of exception which I think is related to the one I had before. Would you please have a look at this one:

Application: X.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Net.Sockets.SocketException
at System.Net.Sockets.Socket.EndConnect(System.IAsyncResult)
at System.Net.ServicePoint.ConnectSocketInternal(Boolean, System.Net.Sockets.Socket, System.Net.Sockets.Socket, System.Net.Sockets.Socket ByRef, System.Net.IPAddress ByRef, ConnectSocketState, System.IAsyncResult, System.Exception ByRef)

Exception Info: System.Net.WebException
at SlackAPI.RequestState`1[[System.__Canon, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].GotResponse(System.IAsyncResult)
at System.Net.LazyAsyncResult.Complete(IntPtr)
at System.Net.ContextAwareResult.CompleteCallback(System.Object)
at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)
at System.Net.ContextAwareResult.Complete(IntPtr)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(System.Object, IntPtr)
at System.Net.HttpWebRequest.SetResponse(System.Exception)
at System.Net.HttpWebRequest.SetAndOrProcessResponse(System.Object)
at System.Net.ConnectionReturnResult.SetResponses(System.Net.ConnectionReturnResult)
at System.Net.Connection.CompleteConnectionWrapper(System.Object, System.Object)
at System.Net.PooledStream.ConnectionCallback(System.Object, System.Exception, System.Net.Sockets.Socket, System.Net.IPAddress)
at System.Net.ServicePoint.ConnectSocketCallback(System.IAsyncResult)
at System.Net.LazyAsyncResult.Complete(IntPtr)
at System.Net.ContextAwareResult.Complete(IntPtr)
at System.Net.LazyAsyncResult.ProtectedInvokeCallback(System.Object, IntPtr)
at System.Net.Sockets.BaseOverlappedAsyncResult.CompletionPortCallback(UInt32, UInt32, System.Threading.NativeOverlapped*)
at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32, UInt32, System.Threading.NativeOverlapped*)

[RyanMathewson]

I just encountered the same issue @miladamirzadeh originally posted while using the v1.0.5.93 NuGet package. Will the package be updated to include the patch any time soon?

[vonzepp]

Hello, Is it possible to merge this fix and update nuget package, please?