Hi Nikhil,
This seems to be shared memory issue .Please do following
1.Stop the application and kill all the old running process
2.cleanipc <instno> remove(for all the instances)
3.check if there are any shared memory or semaphores still present using below
ipcs|grep -i <sidadm> or <orasid>
ipcrm -m <PID> command to kill shared memory process
ipcrm -s <PID> command to kill semaphores
4.Start the applicaitons
Regards,
Murali