Error when supervisor opens interview on the server

The Statistical Office has installed a local server with the latest version 22.06.10 (build 32984).
Everything works fine, but when a supervisor or Headquarters user opens an interview on the server, it opens it and after one second only shows “error”.

This is in the browser log:

Any idea what could have gone wrong during server installation?

Thank you

Maybe this is more readable:

Check the web sockets as described here:

Thank you @sergiy, the IT department now reports having fixed the problem.
Thanks again for the speedy reaction.


Please encourage the specialist to share the steps to rectify this problem that they find successful.

Maria Onea from the IT department sent me the following explanation:

The web application is accessed from the Internet through a reverse proxy based on ”nginx”. It has been discovered that ”nginx” was not configured to forward WebSocket connections.


The following lines were added to ”nginx” configuration file:

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

After reloading ”nginx” the errors disappeared and the application was accessed normally.


Dear Klaus,

thank you very much for including this useful description.

Best, Sergiy