Error
Error Code:
4156
MySQL Error 4156: System Variable Modification in Read-Only Mode
Description
This error occurs when an attempt is made to modify a MySQL system variable while the database server or the current session is operating in a read-only state. In read-only mode, MySQL prevents changes to configuration variables to maintain data integrity and system stability.
Error Message
Cannot change the '%s' system variable in read-only mode.
Known Causes
4 known causesGlobal Read-Only Mode Enabled
The MySQL server instance is configured with the `super_read_only` or `read_only` system variable set to ON, preventing any system variable modifications.
Replication Slave Read-Only
The server is a replication slave that is intentionally set to read-only to prevent accidental writes, including system variable changes, ensuring data consistency.
Application Attempting Modification
A connected application or script is trying to alter a system variable without verifying the current server's read-only configuration.
Manual Read-Only Configuration
A database administrator may have manually set the server to read-only mode for maintenance, specific operational requirements, or security hardening.
Solutions
Coming SoonDetailed step-by-step solutions for this error are being prepared. In the meantime, try these general troubleshooting tips:
General Troubleshooting Tips
- Check the error message carefully for specific details
- Review recent changes that might have caused the error
- Search for the exact error code in the official documentation
- Check log files for additional context
- Try restarting the application or service