There was an update to have rows in 5.3.9 that added a new function the_row_index(). Before this update you could call have_rows('field_name, $post_object), in other words you could use$postin a loop instead of using$post->ID. After the updatehave_rows()` would always return false when using a post object. This was to do trying to convert the post object to a string before getting the valid post id, and this caused a PHP error.
If you were using a repeater, and a post object was used when executing have_rows(), the PHP error during could have cause any number of things to go wrong.
