Go to assignment as teacher/admin and click on "View/grade all submissions"

Invalid get_string() identifier: 'filternotsubmitted' or component 'assign'. Perhaps you are missing $string['filternotsubmitted'] = ''; in mod/assign/lang/en/assign.php?
line 293 of /lib/classes/string_manager_standard.php: call to debugging()
line 6885 of /lib/moodlelib.php: call to core_string_manager_standard->get_string()
line 52 of /mod/assign/gradingoptionsform.php: call to get_string()
line 191 of /lib/formslib.php: call to mod_assign_grading_options_form->definition()
line 3084 of /mod/assign/locallib.php: call to moodleform->moodleform()
line 3175 of /mod/assign/locallib.php: call to assign->view_grading_table()
line 521 of /mod/assign/locallib.php: call to assign->view_grading_page()
line 53 of /mod/assign/view.php: call to assign->view()