mysqli_connect(): Too many connections

Symptoms

You may receive errors like the following on your website, or when trying to access MySQL from the command line or phpMyAdmin.

CONFIG_TEXT: mysqli_connect(): (08004/1040): Too many connections

CONFIG_TEXT: mysqli_real_connect(): (HY000/1040): Too many connections

Description 

This occurs when MySQL has reached its max_connections limit. Once the limit is reached, MySQL will no longer accept connections.

Workaround

1. Check for sleeping queries with the following command.

   # mysql -e "show processlist"|grep -c Sleep

2. Compare that against the max_connections setting for MySQL.

   # mysql -e "show variables like 'max_connections'"

3. Edit /etc/my.cnf.
   • If a large portion of the max_connections is being used by sleeping queries, you might consider lowering the wait_timeout setting.
   • If there are not many sleeping queries, or if you have server resources to spare, you might consider raising the max_connections setting.

4. Restart MySQL.

   # /scripts/restartsrv_mysql

Additional Resources

How to edit a file on command-line