Thanks for the reply.
This note suggests to define a new INV manager.and keep the number of processes to atleast 3, because a new data group might be used besides standard data group.
It seems the concurrent manager is using Standard Data group only in our instance and also i have increased the number of processes to 3.
But still its showing the same error.
Please select the newly created manager i.e: "INV Remote Procedure", under Concurrent > Manager > Administer
Then click on Processes button, and upload the Manager log content ( NOT Internal Manager log) to a free hosting site and provide the link here.
In addition to that also please recheck the application and database log file for any errors, and provide them here.
Also please note, if this is a PRODUCTION environment ensure you raise an SR simultaneously.
The issue is resolved.
We have applied a Patch: 12923944:R12.FND.B as suggested in PO Document Approval Manager (POXCON), Receiving Transaction Manager (RCVOLTM) and INV Remote Procedure Manager (INCTM) Do Not Start / Die After Restart (Doc ID 1413393.1)
We have recently applied the R12.ATG_PF.B.delta.3 which has caused the issue.
Thanks for the suggestions and support.