Why Does My MySQL Connection Keep Dropping with the 'MySQL Server Has Gone Away' Error?

Understanding the "MySQL Server Has Gone Away" Error

When working with scripts that execute repetitive PDO prepared statements, it's possible to encounter an error indicating "MySQL server has gone away." This error often occurs after a certain number of successful executions, particularly in environments with MySQL version 5.0.77 and PHP version 5.2.12.

Cause of the Error:

The root cause of this issue lies in exceeding the maximum packet size allowed by the MySQL server. For example, when inserting large BLOB objects, the packet size can exceed the configured limit.

Error Message in Client and Server Logs:

On the client side, the error manifests as "MySQL server has gone away." In the server log (if error logging is enabled), you may see the following message:

Error 1153 Got a packet bigger than 'max_allowed_packet' bytes

Resolution:

To fix this error, you need to adjust the max_allowed_packet setting in your MySQL configuration file (my.ini or similar). Here's how:

1. Identify the maximum size of BLOB objects you plan to insert.
2. Open the MySQL configuration file and locate the [mysqld] section.
3. Add the following line to the section:

max_allowed_packet = [SIZE]

where [SIZE] is the desired maximum packet size in bytes. For example, to set the maximum packet size to 200 megabytes:

[mysqld]
...
max_allowed_packet = 200M
...

4. Save the configuration file and restart MySQL.

Additional Considerations:

• Verify that you have properly closed any open connections or prepared statements after use.
• If you continue to experience issues, check other MySQL settings such as net_write_timeout and connect_timeout.
• Consider upgrading to a newer version of MySQL and PHP, as they may provide more robust handling of large data packets.

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