Unable to access the Drupal website: Insufficient value for max_allowed_packet option

Symptoms

• Unable to access the Drupal website with the error:

  CONFIG_TEXT: 500 error

  ---

  CONFIG_TEXT: Additional uncaught exception thrown while handling exception

• The following error can be found in website logs:

  CONFIG_TEXT: [fcgid:warn] [pid 4997:tid 140222016743168] [client 203.0.113.2:48318] mod_fcgid: stderr: PHP Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 2006 MySQL server has gone away' in /var/www/vhosts/example.com/httpdocs/includes/database/database.inc:2227

Cause

Insufficient value for max_allowed_packet option.

Resolution

1. Log in to the server via SSH.

2. Create a back up for /etc/my.cnf file:

   # cp -p /etc/my.cnf{,.backup}

3. Open the /etc/my.cnf with the vi text editor.

4. Add the following line under [mysqld] section:

   CONFIG_TEXT: max_allowed_packet = 100M

5. Restart MySQL service:

   # systemctl restart mysql 2> /dev/null || systemctl restart mariadb 2> /dev/null