How to fix ERROR 1156: Got packets out of order in MySQL

Check network connectivity between your client and MySQL server. Use network monitoring tools like ping, traceroute, or nslookup to ensure the connection is stable:

ping <mysql_host>
traceroute <mysql_host>
nslookup <mysql_host>

If running MySQL over SSH, verify the SSH tunnel is stable:

ssh -v user@host  # Check for connection drops

High latency or packet loss here is a primary cause of this error.

If the error occurs during large data transfers, increase the max_allowed_packet size. Edit your MySQL configuration file (typically /etc/mysql/my.cnf or /etc/my.cnf):

[mysqld]
max_allowed_packet=256M

[mysql]
max_allowed_packet=256M

Also set it in your MySQL client configuration. Restart the MySQL server:

sudo systemctl restart mysql

Verify the setting took effect:

SHOW VARIABLES LIKE 'max_allowed_packet';

Verify your wait_timeout and interactive_timeout settings. Connect to MySQL and check current values:

SHOW VARIABLES LIKE '%timeout%';

The default is 28800 seconds (8 hours) in MySQL 5.7+. If your operations take longer, increase these in my.cnf:

[mysqld]
wait_timeout=31536000
interactive_timeout=31536000

Restart MySQL and verify the changes applied. Consider whether your client should also have matching timeouts.

If using MySQL Shell, always explicitly specify the protocol to avoid automatic X Protocol fallback:

# Specify the classic MySQL protocol explicitly
mysql --protocol=TCP -u user -p -h host

# Or using URI format with MySQL Shell 8.0+
mysqlsh mysql://user:password@host:3306

Upgrade to MySQL Shell 9.0+ which fixes this issue automatically. For MySQL Shell 8.0 and 8.4, explicitly including the protocol will resolve the error.

Ensure your MySQL client version matches or is compatible with your server version. Check versions:

# Client version
mysql --version

# Server version (connect first, then run)
mysql -u root -p
SHOW VARIABLES LIKE 'version%';

If versions differ significantly, upgrade the client libraries:

# On Ubuntu/Debian
sudo apt-get update && sudo apt-get install mysql-client

# On CentOS/RHEL
sudo yum update mysql-community-client

For language drivers (PHP, Node.js, Python), ensure they use compatible MySQL connector versions.

If you have a firewall, load balancer, or proxy between client and server, temporarily disable them to test if they're causing packet reordering:

# For UFW on Ubuntu
sudo ufw disable

# For iptables
sudo iptables -F

# For firewalld
sudo systemctl stop firewalld

Test your connection:

mysql -u user -p -h host

If the error disappears, reconfigure your firewall to allow MySQL port 3306 properly instead of blocking/reordering packets.

Ensure you're not running multiple concurrent queries on a single connection. Each connection should handle one query at a time:

// Node.js with mysql2 - WRONG: concurrent queries
connection.query('SELECT ...', callback1);
connection.query('SELECT ...', callback2);  // Causes packet ordering

// CORRECT: use connection pool or await
const pool = mysql.createPool({ /* config */ });
pool.query('SELECT ...', callback1);
pool.query('SELECT ...', callback2);  // Pool handles separate connections

For persistent connections, ensure they're being reused properly and not timing out between requests.

Double-check that your database connection configuration has correct values:

# my.cnf or connection config
[client]
host=localhost
user=mysql_user
password=secure_password
port=3306
database=mydb

Common mistakes:
- Wrong hostname (ensure it resolves correctly)
- Using wrong port (MySQL defaults to 3306, not 3307)
- Credentials not matching actual user
- Network host not allowed in MySQL user permissions

Test with explicit connection:

mysql -h localhost -u mysql_user -p -D mydb

If all else fails, restart both services to clear any stuck connection states:

# Restart MySQL server
sudo systemctl restart mysql

# Or on some systems
sudo service mysql restart

# Verify it's running
sudo systemctl status mysql

For your application, restart it as well:

# For Node.js apps
pm2 restart app

# For PHP/Apache
sudo systemctl restart apache2

# For systemd services
sudo systemctl restart yourapp

This clears stuck connections and allows fresh negotiation of protocol parameters.