Plesk Premium Email fails on CloudLinux: Class 'Modules_Kolab_Install_CloudLinux' not found

Symptoms

• While trying to remove Plesk Premium Email it fails with the following error:

  PLESK_ERROR: Class 'Modules_Kolab_Install_CloudLinux' not found

• Plesk Premium Email is installed on CloudLinux.

• However according to the description of the extension, it is supported on the following operating systems only: CentOS 7, Debian 8, Debian 9, Red Hat Enterprise Linux 7, Ubuntu 16.04, Ubuntu 18.04.

• The /usr/local/psa/admin/plib/modules/kolab/library/Install/CloudLinux file is missing in /usr/local/psa/admin/plib/modules/kolab/library/Install folder:

  # ls -l /usr/local/psa/admin/plib/modules/kolab/library/Install
  drwxr-xr-x 2 root root 23 Mar 24 09:26 CentOS
  rw-rr- 1 root root 1420 Mar 24 09:26 CentOS.php
  drwxr-xr-x 2 root root 43 Mar 24 09:26 Debian
  rw-rr- 1 root root 1604 Mar 24 09:26 Debian.php
  drwxr-xr-x 2 root root 23 Mar 24 09:26 RedHat
  rw-rr- 1 root root 1420 Mar 24 09:26 RedHat.php
  drwxr-xr-x 2 root root 42 Mar 24 09:26 Ubuntu
  rw-rr- 1 root root 1763 Mar 24 09:26 Ubuntu.php

Cause

Plesk Premium mail is not supported on CloudLinux:

https://www.plesk.com/extensions/kolab/

Resolution

There is no workaround for now.