EBS R12 - The system has not been taken off maintenance mode completely.

 Hit the patch, restart EBS Server, use IE when landing at Error

 error message:
       The system has not been taken off maintenance mode completely. Please contact your System Administrator.

From the wrong point of view, looks like Maintainance mode is not closed, then adadmin off Maintenance mode Disable Maintenance mode, or reported the same mistake.
 Below SQL server is not in the Maintenance mode:
 select fnd_profile.value ('APPS_MAINTENANCE_MODE') from dual;

 Output: NORMAL

    ('MAINT' Maintainance mode is turned on, 'Normal' said the Maintainance mode off)

Restart the server again, refresh IE, still the same mistake.

Last solution: Close IE, then open the EBS, the error disappeared, IE cache.

Added:       may want the Disable maintainance Mode, then restart, may also be able to solve the problem