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Description

This error indicates that a specific MySQL user account has reached its limit for simultaneous active connections to the server. It occurs when a user attempts to establish a new connection, but they already have more active sessions than allowed by the 'max_user_connections' global or user-specific setting.

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Error Message

User %s already has more than 'max_user_connections' active connections

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Known Causes

4 known causes

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Excessive Application Connections

Applications failing to close database connections properly can lead to a build-up of open connections for a single user.

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High User Activity

A single user account legitimately making many simultaneous connections due to high demand or complex operations.

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Misconfigured 'max_user_connections'

The 'max_user_connections' setting might be too low for the actual workload or application requirements.

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Unclosed Connections

Scripts or client applications that open connections but do not explicitly close them, leading to connection leaks.

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Solutions

4 solutions available

1. Temporarily Increase max_user_connections easy

Quickly resolve the error by increasing the connection limit for the affected user.

1

Connect to your MySQL server as a user with sufficient privileges (e.g., root).

2

Check the current value of `max_user_connections` for the specific user.

SHOW VARIABLES LIKE 'max_user_connections';
SELECT variable_value FROM performance_schema.threads WHERE thread_type = 'USER' AND user = 'your_username';

3

Increase the `max_user_connections` for the specific user. Replace 'your_username' with the actual username and '100' with the desired higher limit. Note: This change is not persistent across server restarts unless applied in the configuration file.

SET GLOBAL max_user_connections = 100;
ALTER USER 'your_username'@'localhost' WITH MAX_USER_CONNECTIONS 100;

4

If the issue is widespread and not specific to one user, you can increase the global `max_user_connections`. This change is also not persistent across server restarts unless applied in the configuration file.

SET GLOBAL max_user_connections = 200; -- Adjust value as needed

2. Identify and Terminate Idle Connections medium

Find and close unnecessary connections to free up resources.

1

Connect to your MySQL server as a privileged user.

2

Identify active connections for the affected user. Look for connections that have been idle for a long time or are associated with processes that should have finished.

SELECT id, user, host, command, time, state FROM information_schema.processlist WHERE user = 'your_username' AND command != 'Sleep' ORDER BY time DESC;

3

Once you've identified the connection(s) to terminate, use the `KILL` command. Replace `connection_id` with the `id` from the previous query.

KILL connection_id;

4

To proactively manage idle connections, consider setting `wait_timeout` and `interactive_timeout` server variables. `wait_timeout` is for non-interactive connections (e.g., from applications), and `interactive_timeout` is for interactive sessions. Reduce these values to automatically close idle connections.

SET GLOBAL wait_timeout = 60; -- Set to 60 seconds (adjust as needed)
SET GLOBAL interactive_timeout = 60; -- Set to 60 seconds (adjust as needed)

3. Optimize Application Connection Handling advanced

Address the root cause by ensuring your application manages database connections efficiently.

1

Review your application's database connection pooling configuration. Ensure that connections are being properly closed or returned to the pool when no longer needed.

2

Implement proper error handling for database operations. If an error occurs during a database interaction, ensure that the connection is still released.

3

Analyze application logs for any recurring connection-related errors or patterns that might indicate a connection leak.

4

Consider implementing a mechanism within your application to periodically check and close idle connections if connection pooling is not robust enough.

4. Permanently Increase max_user_connections in Configuration medium

Make the connection limit increase persistent across server restarts.

1

Locate your MySQL configuration file. Common locations include `/etc/my.cnf`, `/etc/mysql/my.cnf`, or within a `/etc/mysql/conf.d/` directory.

2

Open the configuration file with a text editor (e.g., `nano`, `vim`).

sudo nano /etc/my.cnf

3

Find the `[mysqld]` section. If it doesn't exist, create it. Add or modify the `max_user_connections` directive. You can set a global limit or a limit per user.

[mysqld]
max_user_connections = 200  # Adjust value as needed

# For per-user limits (requires MySQL 5.7.6+ and `ALTER USER` syntax):
# You would typically set this via ALTER USER as shown in Solution 1 for persistence.

4

Save the changes to the configuration file and exit the editor.

5

Restart the MySQL server for the changes to take effect.

sudo systemctl restart mysql

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Related Errors

5 related errors

MySQL Error 1203: User Connections Exceeded