Unable to access Advanced Monitoring in Plesk: Dashboard not found

Symptoms

Advanced Monitoring doesn't show any data but one of the error messages below instead:

PLESK_ERROR: Dashboard not found

CONFIG_TEXT: *If you're seeing this Grafana has failed to load its application files*
1. This could be caused by your reverse proxy settings.
2. If you host grafana under subpath make sure your grafana.ini root_url
setting includes subpath
3. If you have a local dev build make sure you build frontend using:
yarn start, yarn start:hot, or yarn build
4. Sometimes restarting grafana-server can help

Cause

Incorrect permissions inside sw-cp-server proxy directory.

Corrupted installation of the extensions Grafana and Advanced Monitoring.

Resolution

1. Connect to the server via SSH.

2. Make sure that subdirectories of /var/lib/sw-cp-server/proxy are owned by sw-cp-server:sw-cp-server:

   # ls -la /var/lib/sw-cp-server/proxy
   total 48
   drwx------ 12 sw-cp-server root 4096 Jun 16 13:55 .
   drwx------ 7 sw-cp-server sw-cp-server 4096 Jun 14 18:00 ..
   drwx------ 5 sw-cp-server sw-cp-server 4096 Jun 16 14:22 0
   ...
   drwx------ 6 sw-cp-server sw-cp-server 4096 Jun 16 14:23 3

3. In case permissions/ownership are different, remove the proxy directory:

   # rm -rf /var/lib/sw-cp-server/proxy

In case the issue is not resolved,