The server cannot finish writing a temporary or target file because the operating system returned a low-level write error (EE_WRITE).
MySQL Error 3: EE_WRITE appears when the server fails to write a file, usually a temporary table or export, due to disk-space limits, permission issues, or OS quotas. Free space, fix permissions, and move tmpdir to a healthy volume to resolve the problem.
Error writing file '%s' (OS errno %d - %s)
MySQL throws Error 3 (EE_WRITE) when the storage engine asks the operating system to write data and the OS call fails. The error string shows the file path and the underlying OS errno so you can trace the root cause.
The failure can happen while creating a temporary table, writing the binary log, exporting with SELECT ...
INTO OUTFILE, or performing ALTER TABLE that copies data to a new file.
EE_WRITE stops the current statement and rolls back the transaction if possible. Long-running operations may lose progress.
On replication, the source server may continue but the replica can stop if it hits the same disk problem.
Ignoring the error risks data loss or inconsistent backups, so solve it immediately.
Lack of free disk space is the most common trigger because MySQL cannot extend the target file.
Filesystem permissions, OS quota limits, and readonly mounts block the mysqld process from writing even when space exists.
Low-level I/O failures such as bad sectors, inode exhaustion, or reaching the maximum file count per directory also surface as EE_WRITE.
First, read the OS errno in the error log or the message itself.
Errno 28 points to no space left, 13 indicates permission denied, 122 signals quota exceeded.
Free or extend disk space, change tmpdir to a larger volume, or set innodb_temp_data_file_path to a partition with capacity. Correct permissions so the mysqld user owns the directory.
Temp file overflow: Large GROUP BY queries create on-disk temp tables in tmpdir.
Increase tmp_table_size and max_heap_table_size to keep more data in memory or move tmpdir.
SELECT INTO OUTFILE error: Ensure the OUTFILE path is writable by mysqld and secure_file_priv is not restricting the directory.
Monitor disk usage and inode counts with tools like Prometheus or CloudWatch. Set alerts at 80 percent capacity.
Use separate volumes for data, logs, and tmpdir so temp spikes do not fill the data disk.
Enable automatic log purge.
Galaxy’s query insights flag heavy temp-table usage and recommend indexes or LIMIT clauses before the query hits production. The editor’s AI copilot suggests memory-optimized alternatives, lowering the risk of EE_WRITE.
Galaxy’s run history and version control let teams quickly locate the statement that filled disk space and roll back or optimize it.
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mysqld cannot extend a file because the partition is full, often surfaced as OS errno 28.
The operating system forbids writing to the directory or file, returning errno 13 (EACCES).
User, group, or container quotas prevent further writes even when free space exists.
Temporary directories on readonly filesystems block write calls and trigger EE_WRITE.
The partition has free bytes but no free inodes, so new files cannot be created.
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Occurs when MySQL cannot open a file, usually due to a missing path. Unlike EE_WRITE, the failure is at open time, not write time.
OS-level errno that often underlies EE_WRITE. Address by adding storage.
OS errno indicating mysqld lacks write permission, another root cause of EE_WRITE.
Happens during ALTER TABLE rename.
Can be triggered by the same disk permission or quota issues.
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No. While low disk space is common, EE_WRITE covers any write failure, including permission errors, quotas, and hardware I/O faults.
The error log and the SQL error message show the errno number and text after the file path.
Yes. Once space is available and permissions are correct, re-run the failed query. MySQL will resume normal operations.
Galaxy monitors query runtimes and temp-table usage. It flags abnormal spikes that often precede EE_WRITE and suggests optimizations.
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