An insert violated a uniqueness constraint.
WHAT IT MEANS
The code tried to insert a row with a value that must be unique and already exists.
COMMON CONTEXTS
Importing data that already exists A plugin attempting to create something it already created Two processes inserting simultaneously An interrupted operation being retried
DURING AN IMPORT
Importing over existing data. Drop the tables first, then import cleanly.
Importing a full dump into a database that already has content produces this on nearly every row.
DURING NORMAL OPERATION
A plugin conflict, or an operation retried after a partial failure.
Check whether the operation partly succeeded before failing.
THE AUTO-INCREMENT CASE
If the error mentions PRIMARY and an ID, the table's auto-increment counter may be out of step with the data, usually after a partial restore.
Repairing or rebuilding the table resolves it.
WHAT TO DO
Establish whether the data genuinely already exists. If so, the insert should not be happening and the code or the process is wrong.
If it does not, the constraint or the counter is the problem.
