aspnetcore: NullReferenceException in IISHttpContext

Describe the bug

Since updating a website running in Azure App Service to use ASP.NET Core 2.2.0 with in-process hosting, I’ve observed a small number of NullReferenceExceptions being thrown via Application Insights.

System.NullReferenceException:
   at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.GetOriginalPath (Microsoft.AspNetCore.Server.IIS, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
   at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContext.InitializeContext (Microsoft.AspNetCore.Server.IIS, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
   at Microsoft.AspNetCore.Server.IIS.Core.IISHttpContextOfT`1+<ProcessRequestAsync>d__2.MoveNext (Microsoft.AspNetCore.Server.IIS, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at Microsoft.AspNetCore.Server.IIS.Core.IISHttpServer+<HandleRequest>d__27.MoveNext (Microsoft.AspNetCore.Server.IIS, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60)

To Reproduce

Application experiencing the issue was built from this commit: martincostello/website@ee2ca4ba02823b97062924b7dc8f313e6278a3f8

Expected behavior

HTTP request is processed successfully.

Screenshots

Additional context

Add any other context about the problem here. Include the output of dotnet --info

About this issue

Original URL
State: closed
Created 6 years ago
Reactions: 14
Comments: 38 (21 by maintainers)

Most upvoted comments

If I understand this thread correctly, we are supposed to wait for another release and in the meantime this is not causing any harm. But it is really distracting to see these false positives where we expect to see only “real” exceptions. Is there some middleware that you can provide to catch this condition? I do not want to filter this on my side, for fear of eating up an authentic failure. TIA

mxwlf on Sep 5, 2019

I’m glad this will be addressed in 3.0 but will this be addressed in 2.2.x or 2.x?

jeremycook on Apr 23, 2019

Same problem, Azure App Service, asp.net core 2.2 From what I understand - backporting is not happening because “2.2 out of support soon” aka we don’t care enough ? Given that .NET Core 3.0 is not LTS - and LTS release is only scheduled for November 2019 - some people prefer not to move to aspnetcore 3.0 yet. Would you estimate the effort for back porting the fix into 2.2 ?

centur on Oct 11, 2019

@jkotalik or we need to find the module that makes this request and make sure it sets pRawUrl.

@martincostello thank you for your help in figuring this out.

pakrym on Dec 28, 2018

@vsadams could you file another issue saying you are hitting this in 3.0?

jkotalik on Nov 19, 2019

martygriffin on Oct 2, 2019

Update: For us we had preload enabled flag turned on at the Website level. Disabling this fixed the error

Rugved on May 6, 2019

Sorry, I was wrong, this bug was fixed in RS2 update of win 10, AppService is on RS1

pakrym on Jan 25, 2019

Looking at the code in master, it would seem that GetRawUrlInBytes() saw NativeRequest->pRawUrl to be null or empty, and returned null, which then isn’t handled by GetOriginalPath().

https://github.com/aspnet/AspNetCore/blob/85e2147ff037cc9950249fbb9d095ad47ec4184a/src/Shared/HttpSys/RequestProcessing/NativeRequestContext.cs#L141-L151

https://github.com/aspnet/AspNetCore/blob/3c09d644cccdb21801f7a79e1188a1a1212de5d9/src/Servers/IIS/src/Microsoft.AspNetCore.Server.IIS/Core/IISHttpContext.cs#L185-L186

martincostello on Dec 21, 2018