[GH-ISSUE #340] Error 400 on dotnet core + Blazor server application websocket #300

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opened 2026-02-26 06:32:08 +03:00 by kerem · 1 comment

kerem commented

2026-02-26 06:32:08 +03:00

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Originally created by @damianog on GitHub (Mar 27, 2020).
Original GitHub issue: https://github.com/NginxProxyManager/nginx-proxy-manager/issues/340

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";

proxy_set_header Connection $http_connection;

Than after creating the host-proxy all run perfectly.

Here the origin of solution

https://github.com/aspnet/KestrelHttpServer/issues/1263

Originally created by @damianog on GitHub (Mar 27, 2020). Original GitHub issue: https://github.com/NginxProxyManager/nginx-proxy-manager/issues/340 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 https://github.com/aspnet/KestrelHttpServer/issues/1263

kerem

2026-02-26 06:32:08 +03:00

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kerem commented

2026-02-26 06:32:08 +03:00

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@jc21 commented on GitHub (Apr 5, 2020):

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

@jc21 commented on GitHub (Apr 5, 2020): Thanks for doing the investigation. This all makes sense. I'll merge soon.

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starred/nginx-proxy-manager-NginxProxyManager#300

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