Answer
If the ROWKEY column already physically exists in the table, check for existing rows with a NULL ROWKEY value — populate any such NULL rows with a generated GUID directly via SQL first: UPDATE <table_name> SET ROWKEY = SYS_GUID() WHERE ROWKEY IS NULL; COMMIT;, then attempt the Rowkey activation through IFS again. This specific scenario commonly arises when a Rowkey was previously activated, then deactivated, and a later re-activation attempt is being made, or in environments where a related module is installed but a prerequisite table's Rowkey was never activated.