The 'remuiformat' course format does not define the format_remuiformat\output\renderer renderer class. This is required since Moodle 4.0.

• line 1610 of /course/format/classes/base.php: call to debugging()
• line 3548 of /course/lib.php: call to core_courseformat\base->get_renderer()
• line 74 of /theme/remui/layout/common.php: call to core_course_drawer()
• line 30 of /theme/remui/layout/incourse.php: call to require_once()
• line 959 of /lib/classes/output/core_renderer.php: call to include()
• line 875 of /lib/classes/output/core_renderer.php: call to core\output\core_renderer->render_page_layout()
• line 80 of /mod/page/view.php: call to core\output\core_renderer->header()