MySQL throws error 1027 (ER_FILE_USED) when a table, index, or tablespace file is locked by another session, preventing ALTER, DROP, or RENAME operations.
MySQL Error 1027: ER_FILE_USED appears when the file backing a table or index is locked by another process, blocking schema changes. Release the lock by killing or waiting for the holding thread, then rerun your DDL statement to resolve the issue.
%s' is locked against change
Error 1027 occurs when MySQL reports “'%s' is locked against change”. The server blocks your ALTER, DROP, or RENAME because the underlying file or tablespace is in use by another session, backup, or OS-level process.
The lock protects on-disk structures from concurrent modification.
Until the blocking connection finishes, MySQL refuses any DDL that would rewrite or delete the file.
Long-running queries, open cursors, or background operations like OPTIMIZE TABLE can keep a metadata lock on the table file.
Backup tools that copy .ibd files or snapshot volumes may also hold the OS lock.
File-system security software, antivirus scans, or external scripts touching table files can create an exclusive handle that MySQL detects, triggering ER_FILE_USED when you attempt changes.
First, identify the blocking session with SHOW PROCESSLIST or Performance Schema’s metadata_locks view. If safe, KILL QUERY or KILL CONNECTION to free the lock.
Rerun your DDL once the lock disappears.
If an external OS process owns the lock, stop the backup or disable the scanning program temporarily. Restart MySQL only as a last resort, as it will release all file handles.
Schema migrations during peak traffic often fail because an analytics query holds the table for minutes.
Schedule migrations in low-traffic windows or use gh-ost/pt-online-schema-change to avoid direct DDL on the live table.
ALTER TABLE on InnoDB partitioned tables can trigger ER_FILE_USED when another thread updates a single partition. Use LOCK TABLES WRITE before altering or switch to instant ALTER if your MySQL version supports it.
Backup scripts that rsync .ibd files cause intermittent 1027 errors.
Switch to mysqldump, xtrabackup, or snapshot backups that coordinate with MySQL’s locks.
Always check for long transactions before applying DDL. Automation pipelines can poll INFORMATION_SCHEMA.INNODB_TRX and delay deployment until trx_end_time is near.
Use Galaxy’s query history to locate long-running reports and coordinate with teammates.
Galaxy’s AI copilot can refactor queries to reduce lock time, helping minimize ER_FILE_USED incidents.
Error 1205 (Lock wait timeout) arises when a transaction waits too long for a metadata or row lock. The fix is similar: identify and kill blockers or increase innodb_lock_wait_timeout.
Error 1025 (Error on rename) may appear after 1027 if MySQL cannot rename the temp table created during ALTER. Resolve 1027 first, then retry the statement.
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No. It only signals that the file is busy. Data remains intact; you just need to release the lock.
No. Metadata locks are core to crash-safety. Instead, plan DDL during quiet periods or use online schema change tools.
Yes, because restart drops all file handles. Use it only if you can afford downtime and have no safer option.
Galaxy’s live process list and AI query insights expose long-running sessions, letting you kill or optimize them before they block DDL.
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