How to Diagnose and Fix MySQL Error 1027: “‘%s’ is locked against change”

When managing a MySQL database, encountering Error 1027 can be a sign that the system is preventing modifications to a file due to a lock. This error can arise in various scenarios, and understanding how to diagnose and resolve it is crucial for maintaining database integrity and performance. Let’s explore the potential causes of this error and how to address them.

Scenario 1: Explicit File Locks

The error may occur because a file used by MySQL has been explicitly locked by another process, preventing changes.

Identify the process holding the lock using tools like lsof on Linux or Resource Monitor on Windows.

Terminate the process that’s locking the file. In Linux, for example:

lsof /path/to/locked/file
kill -9 PID

Replace PID with the process ID obtained from the lsof command.

Scenario 2: Implicit File Locks

MySQL itself can implicitly lock files during operations like ALTER TABLE, preventing other operations from modifying the file.

Check for running queries that might be causing implicit locks using the SHOW PROCESSLIST command.

Wait for the locking operations to complete or carefully terminate the query if it’s safe to do so.

KILL QUERY query_id;

Replace query_id with the ID of the query from the process list.

Scenario 3: Filesystem-Level Locks

Filesystem-level locks, such as those from network filesystems (NFS) or filesystem snapshots, can cause this error.

Investigate the filesystem and network storage settings for any locking mechanisms.

Consult the documentation for your specific filesystem or network storage to release the lock.

Scenario 4: Operating System Issues

Operating system issues, such as bugs or misconfigurations, can lead to file locks.

Check system logs for any related errors.

Apply system updates, patches, or reconfigure the system to resolve the issue.

Scenario 5: Storage Engine Locks

Storage engines like InnoDB may set locks at the engine level that result in this error.

Check InnoDB engine status with SHOW ENGINE INNODB STATUS.

Address any deadlocks or lock waits as indicated in the engine status.

Scenario 6: Backup or Replication Processes

Backup or replication processes can lock tables or files, causing Error 1027.

Check if there are any ongoing backup or replication processes that might be locking files.

Wait for the backup or replication to finish, or reschedule it for a less busy time.


MySQL Error 1027 can be a challenging issue, but by systematically diagnosing the cause of the file lock and applying the appropriate solution, you can unlock the file and resume normal operations. Remember to always proceed with caution when dealing with file locks to avoid data corruption or loss. Back up your data regularly, and if the issue persists or you’re unsure about the steps to take, seek assistance from the MySQL community or a database professional.

For further information on MySQL error codes and troubleshooting, the MySQL Server Error Codes and Messages documentation can be a valuable resource.

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