Format plugin format_flexible is not found. Using default format_weeks

• line 137 of /course/format/classes/base.php: call to debugging()
• line 198 of /course/format/classes/base.php: call to core_courseformat\base::get_format_or_default()
• line 38 of /course/format/lib.php: call to core_courseformat\base::instance()
• line 1165 of /lib/pagelib.php: call to course_get_format()
• line 55 of /course/info.php: call to moodle_page->set_course()