1. Navigate to user roles;
2. open existing user role and edit it;
3.observe you are in edit form (at the bottom of page there is "Update" button);
4.remove all checkboxes from Access to UI elements;
5. observe error that at least one UI element must be enabled;
6. observe at the bottom of page, the button is switched to "Add" instead of "Update";

The form must not switch to create mode, but remain in update even if there are errors.