<p>MySQL throws error 1824 when it cannot locate or access the parent table referenced by a foreign key definition.</p>
<p>MySQL Error 1824: ER_FK_CANNOT_OPEN_PARENT arises when a foreign key references a table that MySQL cannot open or find, usually because of name mismatches, missing indexes, or insufficient privileges. Confirm the parent table exists, ensure matching indexes, and re-run the ALTER TABLE or CREATE TABLE statement to resolve the issue.</p>
Failed to open the referenced table '%s'
The error appears with the message Failed to open the referenced table '%s'. It signals that MySQL could not open or locate the parent table specified in a FOREIGN KEY clause.
The failure stops CREATE TABLE or ALTER TABLE statements, preventing the foreign key from being created. Fixing it is critical because broken relationships lead to orphaned data and application errors.
The error usually fires during execution of ALTER TABLE ... ADD CONSTRAINT or during table creation when a foreign key references a table that does not exist, is in a different database, or is not accessible within the current session.
It can also happen after a table rename, migration, or restore when metadata is out of sync and MySQL cannot match the referenced table name.
Ignoring the error leaves tables without referential integrity, allowing inconsistent data. Restoring the relationship immediately protects data quality and keeps queries relying on JOINs efficient.
A typo or case-sensitivity mismatch between the referenced table name in the FOREIGN KEY and the actual table name triggers the error.
The referenced table was dropped, not yet created, or resides in another database not specified in the statement.
The parent table lacks an index on the referenced columns, preventing MySQL from validating the relationship.
The executing user lacks SELECT or REFERENCES privileges on the parent table, so MySQL cannot open it.
Using different engines (e.g., InnoDB child referencing MyISAM parent) can block access, because only InnoDB supports foreign keys.
Usually appears together with 1824 when the child table creation fails because the parent table cannot be opened.
Occurs during INSERT or UPDATE when no matching parent row exists, differing from 1824 which happens during definition time.
A generic foreign key failure that may wrap 1824 as its underlying cause.
Yes. MySQL requires an index (usually PRIMARY KEY) on the referenced columns for efficient lookups and to validate the relationship.
No. Both parent and child tables must use InnoDB if you want foreign key support.
On case-sensitive filesystems like Linux, table names are case-sensitive. Match the exact casing in the FOREIGN KEY clause.
Galaxy auto-completes table names from live metadata, reducing typos, and highlights foreign key issues before execution, preventing Error 1824.
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