Roundcube shows a blank page on a Plesk server: Unsupported database driver: in rcube.php

Symptoms

• Roundcube webmail shows a blank page.

• The following error messages is logged in /var/log/httpd/error_log:

  CONFIG_TEXT: [fcgid:warn] [pid 120445] [client 203.0.113.2:51120] mod_fcgid: stderr: PHP Warning: file_put_contents(/usr/share/errors): failed to open stream: Permission denied in /usr/share/psa-roundcube/program/lib/Roundcube/rcube.php on line 1242
  [fcgid:warn] [pid 120445] [client 203.0.113.2:51120] mod_fcgid: stderr: PHP Warning: Configuration error. Unsupported database driver:  in /usr/share/psa-roundcube/program/lib/Roundcube/rcube.php on line 1347

Cause

suexec module is not enabled in Apache configuration.

Resolution

1. Log in to Plesk.

2. Go to Tools & Settings > Apache Web Server.

3. Enable suexec module

4. Apply the changes.