Application Engine processes fails after PeopleTools 8.51 upgrade

After upgrading to PeopleTools version between 8.50.05 to 8.51.13, intermittently the AE process fails to start with variant kind of ORA error. You will also see below message in the AE log.

Could not setup user PSAPPS's credentials for this AE program. Perhaps this AE request is running outside the user's allowed signon times

The same process might run successfully when restarted manually, but may also error again.  

Oracle has reported this issue is caused by a combination of database bug/issue and a peoplesoft issue on PSAESRV process on PeopleTools 8.50 and above.

This issue occurs due to unexpected broken database connection.This is an indication of a database issue, may be caused by either some database bugs or by improper setup/configure problem, e.g. timeout etc.This issue won't be consistent as the next AE process running in the same PSAESRV, as it will reconnect to the database after the first AE process revealed the broken database connection

Oracle Solution:
This issue is fixed now on PeopleTools 8.51.13 and above. Please upgrade the tools or apply the tools patches to fix the issue. 

Refer Oracle PeopleSoft ID's BUG:12693153  and BUG:11607048 for more information.