Domain configuration failed with the following error:
Unable to generate the web server configuration file on the host <hostname.tld> because of the following errors:
Template_Exception: Can not restart web server:
Please resolve the errors in web server configuration templates and generate the file again.
/var/log/plesk/panel.log file contains the following:
Details: [2015-11-14 18:13:11] ERR [util_exec] proc_close() failed ['/opt/psa/admin/bin/apache_control_adapter' '--restart' '--restart-interval' '0' '--http-port' '80' '--https-port' '443' '--graceful'] with exit code 
[2015-11-14 18:13:42] ERR [panel] Apache config (14475211550.23384100) generation failed: Template_Exception: Can not restart web server:
Can not restart web server:
/var/log/plesk/rc_actions.log have the following content:
Trying to graceful service apache2... Failed to get D-Bus connection: Unknown error -1
OS system was not properly upgraded.
Follow instructions provided in the KB article 213373289