altering table returns errno: 168 "Unknown (generic) error from engine"

Trying to alter table structure shows this error message ... although table is empty and just created before doing this alter statement.
ALTER TABLE SUITE_OVERHEIDSLOKET_RELEASE.portal_policy_information MODIFY id INT AUTO_INCREMENT;
ERROR 1025 (HY000): Error on rename of './SUITE_OVERHEIDSLOKET_RELEASE/portal_policy_information' to './SUITE_OVERHEIDSLOKET_RELEASE/#sql-backup-d1586-2f8c9' (errno: 168 "Unknown (generic) error from engine")