<p>The table’s .frm definition does not match the schema stored in MySQL’s data dictionary, so the server refuses to open or import the table.</p>
<p>MySQL Error 1808 ER_TABLE_SCHEMA_MISMATCH means the table definition in the .frm file disagrees with the schema in MySQL’s dictionary. Recreate or reimport the table with matching column definitions, or run mysqldump and restore to align schemas.</p>
Schema mismatch (%s)
MySQL raises error 1808 ER_TABLE_SCHEMA_MISMATCH when it tries to open or attach a table whose stored definition differs from the schema recorded in the data dictionary. The server blocks the operation to protect data integrity because it cannot reconcile the conflicting metadata.
The mismatch usually appears after copying table files, importing tablespaces, restoring backups, or upgrading versions. Fixing it quickly restores application availability and prevents cascading failures in dependent queries.
Copying only .frm or .ibd files without running ALTER TABLE IMPORT TABLESPACE leaves the dictionary out of sync, triggering the mismatch the moment the table is accessed.
Manually replacing a table’s files after CREATE TABLE LIKE introduces column or index differences that MySQL detects at open time.
Replication lag or partial dumps can send an ALTER TABLE downstream while the tablespace is still on the old format, producing the conflict during apply.
Version upgrades introduce new metadata fields or reserved words. If the dictionary upgrade step fails, the old and new definitions diverge and error 1808 surfaces.
Dump and reload is the safest route. Use mysqldump to export, drop the table, then import the dump so MySQL rewrites consistent metadata.
If you still have a matching .ibd and .frm pair, run ALTER TABLE table_name DISCARD TABLESPACE, copy the files, then ALTER TABLE table_name IMPORT TABLESPACE to re-register the structure.
When only data matters, CREATE TABLE new LIKE old, copy rows with INSERT INTO new SELECT * FROM old, then rename to replace the broken table.
During partial restores, always copy both .ibd and .frm and run the IMPORT TABLESPACE statement. Skipping either reproduces error 1808 instantly.
If replication stops, halt the SQL thread, repair the table with the chosen method, then restart replication to clear the error.
After a MySQL upgrade, run mysql_upgrade to refresh dictionary entries and eliminate mismatches.
Prefer logical backups such as mysqldump instead of raw file copies. Logical restores recreate correct metadata automatically.
Execute FLUSH TABLES WITH READ LOCK before copying raw files, ensuring no concurrent changes can drift the schema.
Maintain primary and replica servers on the same major version to reduce metadata incompatibilities.
Error 1805 ER_FK_INCOMPATIBLE_PARENT signals a foreign key mismatch. Reimport both parent and child tables to fix it alongside error 1808.
Error 1813 ER_TABLESPACE_CANNOT_BE_CONVERTED appears when the tablespace format is too old. Dump and reload resolves it similarly.
Moving only .frm or .ibd files without using ALTER TABLE IMPORT TABLESPACE confuses MySQL’s dictionary and triggers a schema mismatch on access.
Upgrading the server or replicating from a newer version introduces metadata fields unsupported by the old instance, causing error 1808.
Restoring a single table while leaving the original tablespace leads to mismatching column definitions and raises the error.
Raised when foreign key metadata on child and parent tables differ. Often fixed by recreating both tables.
Occurs during upgrade when tablespace format is too old. Dump and reload resolves it.
Appears when MySQL cannot find a table after discarding tablespace. Importing or recreating the table clears the error.
If you have the original .ibd and .frm files, importing the tablespace can resolve the mismatch with no data loss.
Logical dumps avoid metadata drift by rebuilding the table, so restoring from mysqldump virtually guarantees you will not see error 1808.
Yes. The replica’s SQL thread halts until you resolve the schema mismatch.
Galaxy tracks schema versions with queries, alerts you to drift, and suggests correct ALTER statements, reducing the chance of mismatches.
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