Why Does My Website Throw a \'Prepared Statement Needs to Be Re-Prepared\' Error After Migration?

Troubleshooting MySQL Error: 'Prepared Statement Needs to Be Re-Prepared'

Upon migrating a website with modified PHP code and MySQL stored procedures from a local environment to a hosting server, a persistent fatal error, "'Prepared statement needs to be re-prepared'," has plagued the site's operation.

Cause of the Error:

The underlying issue could be related to MySQL bug #42041, which affects prepared statement caching. When statement caching is insufficient, the server may fail to reuse prepared statements after a restart, leading to the error.

Solution:

The solution lies in adjusting the server's table_definition_cache variable. This variable sets the maximum number of tables whose definitions are cached in memory. By increasing its value, you can accommodate more cached prepared statements and potentially resolve the error.

Implementation:

To modify the table_definition_cache value, follow these steps:

1. Access your MySQL server using a tool like MySQL Workbench or the command prompt.
2. Connect to the database and run the following command to check the current value:

SHOW VARIABLES LIKE 'table_definition_cache';

3. Set a higher value for table_definition_cache using the following syntax:

SET GLOBAL table_definition_cache = <new-value>;

4. Restart the MySQL server to apply the changes.

Additional Resource:

For further information on prepared statement caching, refer to the official MySQL documentation:
https://dev.mysql.com/doc/refman/8.0/en/statement-caching.html

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