public function upgrade_stale_php_files_page() {
        $output = '';
        $output .= $this->header();
        $output .= $this->heading(get_string('upgradestalefiles', 'admin'));
        $output .= $this->box_start('generalbox', 'notice');
        $output .= format_text(get_string('upgradestalefilesinfo', 'admin', get_docs_url('Upgrading')), FORMAT_MARKDOWN);
        $output .= html_writer::empty_tag('br');
        $output .= html_writer::tag('div', $this->single_button($this->page->url, get_string('reload'), 'get'), array('class' => 'buttons'));
        $output .= $this->box_end();
        $output .= $this->footer();

        return $output;
    }