Plesk and/or websites are inaccessible: SQLSTATE[08004] [1040] Too many connections error

Note: On Linux server with MySQL installed, the max_connections limit cannot be higher than 214, unless the solution from this KB article is applied.

# Automatic Solution

1. Connect to the Plesk server via SSH.

2. Download the script that will set the MySQL parameter max_connections to 300:

   # wget https://raw.githubusercontent.com/plesk/kb-scripts/master/mysql-max-connections/mysql-max-connections.sh

3. Make the script executable:

   # chmod +x mysql-max-connections.sh

4. Execute the script:

   # ./mysql-max-connections.sh

Note: If the automatic solution did not help, apply the manual solution below.

# Manual Solution

1. Connect to the Plesk server via SSH.

2. Find the current max_connections value:

   # plesk db "SHOW VARIABLES LIKE 'max_connections'"
   +-----------------+-------+
   | Variable_name | Value |
   +-----------------+-------+
   | max_connections | 151 |
   +-----------------+-------+

3. Open the MySQL configuration file my.cnf in a text editor. In this example, we are using the vi editor:

   • on CentOS/RHEL-based distributions

     # vi /etc/my.cnf

   • on Debian/Ubuntu-based distributions

     # vi /etc/mysql/my.cnf

4. Increase the number of connections by adding this directive under the [MySQLD] section:

   [mysqld]
   max_connections=300

5. Save the changes and close the file.

6. Restart MySQL/MariaDB service to apply the changes using one of these commands:

   # service mysql restart

   # service mariadb restart