Client does not work in ASP.NET Core

[cmuentes]

The client does not currently seem to work in ASP.NET Core. The handshake fails on the final step (connection upgrade). We tried numerous ways to debug it, including stepping through Socket.IO code and using Wireshark.

We found that Socket.IO is returning an ACK for the connection upgrade, but for some reason until Socket.IO forcibly closes the connection, ASP.NET Core hangs on the final step. Anyone with some time to debug: please see if you can repro and/or get more info. We would be glad to help fix this!

[paintcode]

In my research for my own project, I came across this little note in the ASP.NET Core documentation. I'm not sure if it is relevant to your issue, but I wanted to bring it to your attention.
https://docs.microsoft.com/en-us/aspnet/core/fundamentals/websockets?view=aspnetcore-2.2#disable-websocket-when-using-socketio-on-nodejs