If the identifier of the entity type represents a field in a database table that is not automatically generated, set the Pre-Updater Field property to True. I got this error when I try to insert new record, the ID field cannot be edited. or when I try to modify the existing record.
The workaround (maybe a bug in SharePoint) I found is to unselected the “Read-Only” and “Required” choices for the ID field in “Read Item” operation, remove the list and create the list again.
Then come back to the “Read Item” operation, tick the “Read-Only”choices again, remove the list and recreated.