Knowledge Base

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

Symptoms

The following error message appears in the Plesk interface or during Plesk migration process:

PLESK_INFO: Unable to connect to database: Too many connections
SQLSTATE[08004] [1040] Too many connections
Websites fail to load with the error:

PLESK_INFO: Error Establishing a Database Connection
Plesk license installation fails with the error:

PLESK_ERROR: Incorrect ServerInfo format (Error code: 2)

exit status 1

Cause

The maximum number of simultaneous connections to the MySQL server has been reached and new connections to the server cannot be established.

Resolution

For Plesk on Linux

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

Connect to the Plesk server via SSH.
Download, unzip and run automatic script that will set the MySQL parameter max_connections to 300:

# wget https://support.plesk.com/hc/article_attachments/360003572374/maxconn.zip
# unzip maxconn.zip
# chmod +x maxconn
# ./maxconn

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

Manual Solution

Connect to the Plesk server via SSH.
Find the current max_connections value:

# plesk db “SHOW VARIABLES LIKE ‘max_connections'”
+—————–+——-+
| Variable_name | Value |
+—————–+——-+
| max_connections | 151 |
+—————–+——-+
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
Increase the number of connections by adding this directive under the [MySQLD] section:
```
[mysqld]
max_connections=300
```
Save the changes and close the file.
Restart MySQL/MariaDB service to apply the changes using one of these commands:

# service mysql restart

# service mariadb restart

For Plesk on Windows Server

Manual Solution

Connect to the Plesk server via RDP.
Open the MySQL configuration file %plesk_dir%DatabasesMySQLmy.ini in a text editor.
Increase the number of connections by adding this directive under the [MySQLD] section (the default value is 300):
```
[MySQLD]
max_connections=300
```
Save the changes and close the file.
Restart the MySQL/MariaDB service.