How to Fix “Too Many Connections” Error in MySQL

If you see the error:

“ERROR 1040 (08004): Too many connections”
your MySQL server has reached its max_connections limit.

What Causes This?

• Application leaking connections (not closing)
• Slow queries blocking connections
• Connection pool misconfigured
• Low max_connections default (151)

How to Fix

1. Check Current Connection Usage

SHOW STATUS WHERE variable_name = 'Threads_connected';
SHOW VARIABLES LIKE 'max_connections';

2. Temporarily Increase Limit

SET GLOBAL max_connections = 500;

3. Make It Persistent

Edit my.cnf:

[mysqld]
max_connections = 500

4. Find Idle/Hanging Connections

SHOW PROCESSLIST;

Kill problematic threads or fix your app logic.