After upgrade to OA 7.0 failed tasks like below are present in the Task Manager:
Task ID 100001 Task name Send "Send link for change password" mail to user user01 Task description Task that sends a "Send link for change password" mail to firstname.lastname@example.org for user user01 (1000001) Queue status Failed Start not earlier than Jan-01-2017 10:00 Method name taskSendLocalizedEMail on SCREF:Notifier:0 Last execution output The remote server is down, details: system exception, ID 'IDL:omg.org/CORBA/OBJECT_NOT_EXIST:1.0' OMG minor code (2), described as 'Failed to create or locate Object Adapter.', completed = NO
taskSendLocalizedEMail method that is used in these tasks is no longer present in OA 7.0. The tasks were most probably scheduled before the upgrade and initially failed with different errors, which can be checked in the Task Log.
Cancel all the tasks that fail in the same manner - they will not be processed. New tasks of similar nature should be scheduled.