Error
Error Code:
3857
MySQL Error 3857: Slave Thread Blocked by Backup Lock
Description
This error occurs when an attempt is made to stop the MySQL replication slave SQL thread while the entire database instance is currently locked for a backup operation. The instance lock prevents operations that could interfere with data consistency during the backup, including stopping critical replication processes like the slave SQL thread.
Error Message
Cannot stop the slave SQL thread while the instance is locked for backup. Try running `UNLOCK INSTANCE` first.
Known Causes
3 known causesInstance Locked for Backup
The MySQL instance has been placed into a global read lock (e.g., via `FLUSH TABLES WITH READ LOCK` or `LOCK INSTANCE FOR BACKUP`) to ensure data consistency during an active backup process.
Unreleased Instance Lock
A previous backup or administrative task may have locked the instance, and the corresponding `UNLOCK INSTANCE` command was not executed, leaving the lock active indefinitely.
Concurrent Operations Conflict
An operation to stop the replication slave SQL thread was executed concurrently with a backup process that initiated an instance-wide lock, leading to a timing conflict.
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