Application Engines not working properly with PT 8.50.23

Hi Gurus,

I need help.

Problem description
----------------------------
We are on PT 8.50.23 and PS application version is 8.9. We are facing issues while running application engine programs in Unix scheduler. Some of the application engine programs don't start and it gives us an error like " Process Request shows status of 'INITIATED' or 'PROCESSING' but no longer running " in the message log. When I checked the process scheduler log it shows something "File: /vob/peopletools/src/psmgr/mgrvers.cppSQL error. Stmt #: 879 Error Position: 0 Return: 8055 - Cursor entry has not been initialized (SQLSTATE PS055)
Failed SQL stmt:SELECT VERSION FROM PSVERSION WHERE OBJECTTYPENAME = 'SYS'