MySQL error 1033 (ER_NOT_FORM_FILE) means the server cannot interpret a MyISAM or ISAM table file because its internal format, header, or metadata is corrupted or mismatched.
MySQL Error 1033: ER_NOT_FORM_FILE signals that a table file’s format or header is unreadable, often after an abrupt shutdown, disk issue, or incompatible file copy. Run CHECK TABLE, REPAIR TABLE, or recreate the table from a backup to restore normal operation.
Incorrect information in file: '%s'
Error 1033 appears when MySQL encounters a .MYD, .MYI, or .ISD file whose internal format flag does not match what the storage engine expects. The server therefore refuses to open the table and returns “Incorrect information in file: '%s'”.
The problem is strictly file-level: the SQL syntax is valid, but the underlying on-disk representation is damaged or belongs to an incompatible MySQL version.
Until the file is repaired or replaced, any query that touches the table will fail.
File corruption is the leading trigger. Sudden power loss, forced kills, or kernel panics can leave page headers half-written. MySQL then sees impossible record offsets and throws ER_NOT_FORM_FILE at startup or on first access.
Version mismatch is another source. Copying MyISAM files from a newer MySQL release to an older one introduces header fields the old server cannot parse.
The same happens when the .frm definition was altered but the data files were not rebuilt.
Begin with CHECK TABLE tbl_name EXTENDED. If MySQL confirms corruption, issue REPAIR TABLE tbl_name QUICK or MEDIUM. These commands rebuild the index file and align header metadata without touching data rows.
When REPAIR fails, dump the table structure with SHOW CREATE TABLE, rename the broken files, recreate the table, and load data from a consistent backup.
Galaxy users can run these commands directly in the editor, commit the repaired query, and share it for peer review.
Scenario: server restarts after crash and several MyISAM tables refuse to open. Solution: run myisamchk -r /var/lib/mysql/db/*.MYI while MySQL is stopped, then start the server and verify with CHECK TABLE.
Scenario: copied tables from MySQL 5.7 to 5.6 for testing.
Solution: export with mysqldump on 5.7 and import the SQL file into 5.6 instead of copying raw files.
Use InnoDB for transactional tables; it writes in a crash-safe format and avoids most ER_NOT_FORM_FILE incidents. When you must keep MyISAM, enable the myisam_recover_options config so MySQL auto-repairs on startup.
Schedule regular CHECK TABLE on low-traffic windows.
Galaxy’s task scheduler can automate these checks and alert on failures, preventing surprises in production.
ER_NOT_KEYFILE (1034) occurs when the index file is corrupt rather than the data file. REPAIR TABLE usually resolves both errors simultaneously.
ER_TABLE_CORRUPT (144) happens on InnoDB when dictionary entries do not match physical pages. Running innodb_force_recovery or restoring from backup corrects the inconsistency.
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An unexpected power loss or kill -9 leaves page headers incomplete, producing unreadable format bits.
Bad sectors or silent data corruption alter bytes inside .MYD or .MYI files, breaking the internal record structure.
Copying MyISAM files from a newer MySQL build to an older one introduces unknown header flags.
Restoring only .MYD without matching .MYI or .frm causes metadata mismatch that triggers ER_NOT_FORM_FILE.
Changing the .my.cnf character set, row format, or altering files with hex editors leaves inconsistent metadata.
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If REPAIR TABLE works, you can run it online. For severe corruption, stop the server and use myisamchk, which requires downtime.
No. ER_NOT_FORM_FILE is specific to MyISAM and ISAM storage engines. InnoDB uses different error codes for corruption.
Yes. InnoDB is crash-safe and does not rely on external index files, eliminating most file-format issues.
Galaxy’s scheduled CHECK TABLE jobs surface corruption early, and its collaboration tools let teams share the repair scripts instantly.
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