6 calls to drupal_maintenance_theme()

authorize.php in drupal/core/authorize.php
Administrative script for running authorized file operations.
drupal_flush_all_caches in drupal/core/includes/common.inc
Flushes all persistent caches, resets all variables, and rebuilds all data structures.
install_begin_request in drupal/core/includes/install.core.inc
Begins an installation request, modifying the installation state as needed.
MaintenanceModeSubscriber::onKernelRequestMaintenance in drupal/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
Returns the site maintenance page if the site is offline.
update.php in drupal/core/update.php
Administrative page for handling updates from one Drupal version to another.
_drupal_log_error in drupal/core/includes/errors.inc
Logs a PHP error or exception and displays an error page in fatal cases.