From https://www.drupal.org/project/drupal/issues/331631:
Drupal users using admin_menu no longer visit the page on the path "admin". That's the only page where Drupal checks the system state.
In #317136: Add status report/update status warnings as icon(s), the idea of displaying the current system (severity) status as icon in the Administration menu evolved. However, admin_menu certainly cannot invoke system_status(TRUE) on all page requests.
So, the goals of this issue:
1) Store current system status in a variable, making it accessible to other modules.
2) Shortcut checking for the current system status. If we already know there is an error, we do not need to perform the full test again.
3) Display system status on all admin pages.
Attached patch tries to do this, however fails to do so. How is Update module maintaining the proper state of its message?