Unable to start Apache on a Plesk server: Unable to find IPv4 address of server.example.com

Symptoms

• Apache fails to start. One of the following error messages appears in the Apache error log file:

  • on CentOS/RHEL-based distributions: /var/log/httpd/error_log

  • on Debian/Ubuntu-based distributions: /var/log/apache2/error.log

  CONFIG_TEXT: (EAI 2)Name or service not known: AH01564: unable to find IPv4 address of "server.example.com"
  AH00016: Configuration Failed

  ---

  CONFIG_TEXT: (EAI 3)Temporary failure in name resolution: AH01564: unable to find IPv4 address of "ip-203-0-113-2"
  AH00016: Configuration Failed

• The following email notification might be sent to Plesk administrator:

  CONFIG_TEXT: Unable to generate the web server configuration file on the host <server.example.com> because of the following errors: Template_Exception: Can not restart web server: file: /opt/psa/admin/plib/Service/Driver/Web/Server/Apache.php line: 109 code: 0

  ---

  CONFIG_TEXT: Unable to generate the web server configuration file on the host <server-hostname> because of the following errors:
  Template_Exception: Can not restart web server: Apache is down, start it instead of graceful Apache is down, start it instead of graceful

Cause

There is no IPv4 address specified in the /etc/hosts file for the server name configured in /etc/hostname file.

Resolution

1. Log in to Plesk.

2. Go to Tools & Settings > Server Settings.

3. In the Full hostname field, set the server hostname.

4. Click OK.

5. Go to Tools & Settings > Services Management and make sure Web Server (Apache) is started.