function system_update_8802 in Drupal 8

Fix system.theme:admin when the default theme is used as the admin theme.

File

core/modules/system/system.install, line 2652

Install, update and uninstall functions for the system module.

Code

function system_update_8802() {
  $config = Drupal::configFactory()
    ->getEditable('system.theme');

  // Replace '0' with an empty string as '0' is not a valid value.
  if ($config
    ->get('admin') == '0') {
    $config
      ->set('admin', '')
      ->save(TRUE);
  }
}