Plesk pre-upgrade check provides incorrect report: There are custom web server configuration templates at /opt/psa/admin/conf/templates/custom

Symptoms

• Plesk pre-update checker reports the warning:

  Warning:
  Plesk pre-upgrade check
  WARNING: There are custom web server configuration templates at /opt/psa/admin/conf/templates/custom. These custom templates might be incompatible with a new Plesk version, and this might lead to failure to generate web server configuration files. Remove the directory to get rid of this warning. Please check https://support.plesk.com/hc/articles/213399669 for details.

• There are no files inside the /opt/psa/admin/conf/templates/custom, however, the directory itself is present on the server:

  # # ls -la /opt/psa/admin/conf/templates/custom
  total 8
  drwxr-xr-x 2 root root 4096 Dec 1 11:51 .
  drwxr-xr-x 5 root root 4096 Dec 1 11:51 ..

Cause

Incorrect error reporting. This is the bug PPPM-13806, which will be solved in future Plesk updates.

Resolution

Until the bug be fixed the warning can be safely ignored.