Invalid websocket upgrade about nicegui HOT 4 CLOSED

I solved it. It obvioulsy had nothing to do directly with NiceGUI but with the reverse proxy setup on nginx. I leave the solution here in case someone faces the same problem:

I solved it by adding the following configuration to my nginx config file:

proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "Upgrade";

thanks to this source: https://www.nginx.com/blog/websocket-nginx/

from nicegui.

Interestingly I had exactly the same issue Invalid websocket upgrade (further occurrences of this error will be logged with level INFO). However, I am using Apache instead of nginx.

For reference, this is the Apache config that works for me in combination with nicegui (1.4.22). Maybe this could also be helpful as an example in the repository since the translation from nginx to Apache was not trivial (at least for me).

<VirtualHost server.name.org:80>
    # only used for mapping HTTP to HTTPS
    RewriteEngine On
    RewriteCond %{HTTPS} off
    RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
    RewriteCond %{SERVER_NAME} =server.name.org
    RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]
    ServerName server.name.org
</VirtualHost>

<VirtualHost server.name.org:443>

    # SSL configurations would go here...
    
    RequestHeader set X-Forwarded-Proto "https"
    
    ServerName server.name.org
    ServerSignature Off
    
    # below the important parts required for WS to work 
    RewriteEngine On
    RewriteCond %{HTTP:Connection} Upgrade [NC]
    RewriteCond %{HTTP:Upgrade} websocket [NC]
    RewriteRule /(.*) ws://127.0.0.1:8080/$1 [P,L]
    
    ProxyPreserveHost On
    
    <Location />
        ProxyPass http://127.0.0.1:8080/
        ProxyPassReverse /
    </Location>
</VirtualHost>

from nicegui.

We have such a configuration in one of our examples: https://github.com/zauberzeug/nicegui/tree/main/examples/nginx_subpath. Maybe it is not visible enough?

from nicegui.

That looks very helpful indeed @j4nSolo. Would you like to create a pull request with a apache_subpath example similar to the existing nginx_subpath?

from nicegui.