Error message is showing in Plesk while configuration file exists: Unable to generate the web server configuration file

Symptoms

• On Plesk Home page an error page is shown:

  PLESK_ERROR: Unable to generate the web server configuration file on the host <example.com> because of the following errors:
  Template_Exception: httpd: Syntax error on line 353 of /etc/httpd/conf/httpd.conf: Syntax error on line 6 of /etc/httpd/conf.d/zz010_psa_httpd.conf: Could not open configuration file /etc/httpd/conf/plesk.conf.d/webmails/example.com_webmail.conf: No such file or directory
  file: /usr/local/psa/admin/plib/Template/Writer/Webserver/Abstract.php
  line: 75
  code: 0
  Please resolve the errors in web server configuration templates and generate the file again.

• Plesk admin receives emails with the same error;
• The file from the error exists:

  # ls -la /etc/httpd/conf/plesk.conf.d/webmails/example.com_webmail.conf
  -rw------- 1 root httpd 188 Apr 10 14:22 /etc/httpd/conf/plesk.conf.d/webmails/example.com_webmail.conf

• Apache configuration test is successful:

  # httpd -t
  Syntax OK

Cause

This is due to Plesk bug #PPPM-6752, which will be fixed in future updates.

Resolution

The behaviour carries a cosmetic character, as everything works as expected.

Error can be safely ignored.