Error 400 on dotnet core + Blazor server application websocket

[damianog]

I deployed a dotnet core application based on Blazor that make use of websocket communication.
a simple post on the host-proxy caused an Error 400 page

I am running the docker nginx proxy manager image v2.2.0
I configured my host-proxy by enabling with an SSL certificarte

I managed to fix this strange behavior by editing the template file:

/app/templates/proxy_host.conf

and changed the following line

proxy_set_header Connection "upgrade";

in

proxy_set_header Connection $http_connection;

Than after creating the host-proxy all run perfectly.

Here the origin of solution

aspnet/KestrelHttpServer#1263

[jc21]

Thanks for doing the investigation. This all makes sense. I'll merge soon.