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How to Increase MySQL max_connections

The max_connections system variable sets the maximum permitted number of simultaneous client connections.

If you are seeing "Too many connections" errors, increasing the max_connections may help resolve the problem.

It is important to monitor server resource usage before and after adjusting max_connections. Increasing the maximum connections will result in higher memory usage.

The default value for this setting is 151 and the maximum is 100,000 (in MySQL 8.0). When adjusting this setting, try 2x the initial setting. The effective maximum connections will always be less than the open files limit (open_files_limit - 810).

You can use ServerPilot's MySQL monitoring dashboards to know whether you need to increase the size of the max_connections setting.

Change the MySQL max_connections setting

Create file:

/etc/mysql/conf.d/max_connections.cnf

with contents (e.g. to double the default of 151 to 300):

[mysqld]
max_connections = 300

You can run the following command as "root" to create the configuration file shown above:

echo -e '[mysqld]\n''max_connections = 300' > /etc/mysql/conf.d/max_connections.cnf

Restart MySQL:

sudo service mysql restart

Check the new value of the variable with:

sudo mysql -e "SHOW VARIABLES LIKE 'max_connections';"