MySQL error code
MySQL error 1821
MySQL server error 1821 is ER_FK_NO_INDEX_CHILD, reported with SQLSTATE HY000.
Failed to add the foreign key constraint. Missing index for constraint '%s' in the foreign table '%s'
| Error | 1821 |
|---|---|
| Name | ER_FK_NO_INDEX_CHILD |
| SQLSTATE | HY000 |
| Group | Server errors |
Source: MySQL 8.4 Error Reference