This page should be using theme serenity which cannot be initialised. Falling back to the site theme classic

• line 704 of /lib/outputlib.php: call to debugging()
• line 1553 of /lib/pagelib.php: call to theme_config::load()
• line 1960 of /lib/setuplib.php: call to moodle_page->initialise_theme_and_output()
• line 62 of /course/info.php: call to bootstrap_renderer->__call()