ASP.NET Core 2.1 Invalid Request Line Issue

c# asp.net-core kestrel-http-server
Yang picture Yang · Jul 23, 2018 · Viewed 11.4k times · Source

Our Linux Docker ASP.NET Core container server logs are getting filled by the following 'Informational' log entries since we've updated from .NET Core 2.0 to .NET Core 2.1 (SDK 2.1.302):

INFO|Microsoft.AspNetCore.Server.Kestrel|Connection id "0HLFG42JUAORG" bad request 
data: "Invalid request line: 
'CNXN\x00\x00\x00\x01\x00\x00\x04\x00\x1B\x00\x00\x00M\x0A'" 
Microsoft.AspNetCore.Server.Kestrel.Core.BadHttpRequestException: Invalid 
request line: 'CNXN\x00\x00\x00\x01\x00\x00\x04\x00\x1B\x00\x00\x00M\x0A'

INFO|Microsoft.AspNetCore.Server.Kestrel|Connection id "0HLFG42JUAORH" bad request 
data: "Invalid request line: 
'CNXN\x00\x00\x00\x01\x00\x00\x04\x00\x1B\x00\x00\x00M\x0A'" 
Microsoft.AspNetCore.Server.Kestrel.Core.BadHttpRequestException: Invalid 
request line: 'CNXN\x00\x00\x00\x01\x00\x00\x04\x00\x1B\x00\x00\x00M\x0A'

The connection ID is incrementing by 1 alpha/digit every second or so. The hex doesn't seem translate to anything meaningful (NUL NUL NUL SOH NUL NUL EOT NUL ESC NUL NUL LF).

Things we've ruled out:

  • It's not originating from WAN/LAN (disabled network access to the containers and the entries are still being generated).
  • It doesn't occur in our development environment (windows w/ Visual Studio)
  • Redeploying the docker container doesn't fix the issue.
  • We don't believe it to be an SSL issue since kestrel is configured for http only. We can access the app and it's websockets (SignalR) over https and wss

Answer

Gurgen Sargsyan picture Gurgen Sargsyan · Sep 21, 2019

It looks like you're hitting an HTTP endpoint over HTTPS.

Related questions

How do I get the kestrel web server to listen to non-localhost requests?

I've deployed my c#, asp.net 5, mvc 6 app to a windows 2008 server. I've fired up dnx web and it is listening to port 5000 and works fine when accessing from local computer. How do I get it to listen to non-localhost …

Read More
How to get a Console output in ASP.NET Core with IIS Express

ASP.Net Core documentation here has a nice console logging output like in the picture below with colors for various LogLevels. I have now created an application in Visual Studio and I see that it now runs behind IIS Express …

Read More
Setting index.html as default page in asp.net core

How can I get asp.net core to serve an index.html file from inside my wwwroot? The reason I want to do this is because I an developing an angular 4 app using the angular CLI and it takes care …

Read More