Websites configured with PHP 7.2 or lower version fail to establish a database connection after updating MariaDB to v10.2.35 or v10.3.26: Malformed communication packet

Symptoms

• Websites configured with PHP 7.2 or lower version are unavailable when establishing a database connection and the following error message is shown:

  SQLSTATE[HY000]: General error: 1835 Malformed communication packet

• MariaDB server has been updated to v10.2.35 or v10.3.26 versions:

  # mysql -V
  mysql Ver 15.1 Distrib 10.2.35-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2

• Error in Domains > example.com > Logs:

  AH01071: Got error 'PHP message: PHP Warning: mysqli_query(): MySQL server has gone away in /var/www/vhosts/example.com/httpdocs/wp-includes/wp-db.php on line 2033nPHP message: PHP Warning: mysqli_query(): Error reading result set's header in /var/www/vhosts/example.com/httpdocs/wp-includes/wp-db.php 

Cause

This issue is caused by the MariaDB bug with ID #MDEV-24121. Which was fixed by MariaDB on versions 10.2.36, 10.3.27, 10.4.17, and 10.5.8.

Resolution

The next packages update is already available, so if the server has been affected, install the lastest MariaDB updates:

1. Log into Plesk

2. Go to Tools & Settings > System Updates

3. Search for “MariaDB”

   

4. Choose all the packages and click Update

Alternatively, updates can be installed via CLI: