Why Does My MySQL Connection Fail with 'Server Has Gone Away,' and How Can I Fix It?

Tackling the MySQL "Server has Gone Away" Error

Running a server to process files and report results to a remote MySQL server can occasionally lead to a frustrating error: "2006, MySQL server has gone away." This can occur when the files processing takes a significant time, and the connection between the client (office server) and MySQL server times out.

While the "wait_timeout" setting has been mentioned as a potential solution, it's important to note that it refers to the server that your office is running. Adjusting this setting may not resolve the issue if the problem lies with the remote MySQL server.

Uncovering the Root Cause

In most cases, the true culprit is a low default setting for "max_allowed_packet," which limits the maximum size of data that can be sent in a single packet between the client and server. Processing large files may require packets larger than the default limit, causing the server to drop the connection.

Enhancing Packet Size

To rectify this, modify the "max_allowed_packet" setting in the "/etc/my.cnf" file (under [mysqld]) on your office server. Increasing it to a higher value, such as 8M or 16M, typically eliminates the error. However, it's important to choose a size appropriate for your specific requirements.

Additional Notes for Configuration

• If the line for "max_allowed_packet" does not exist in the configuration file, add it as an entry beneath [mysqld].
• Changes made to the configuration file will only persist after restarting the MySQL daemon. Alternatively, you can use the command "SET GLOBAL max_allowed_packet=104857600" to set the value temporarily to 100MB.
• On Windows systems, ensure that the "my.ini" or "my.cnf" file is saved with ANSI encoding, not UTF-8.

By addressing the "max_allowed_packet" setting, you can effectively mitigate the "MySQL server has gone away" error and ensure a stable connection between your office server and the remote MySQL server during file processing.

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