ORA-07445: exception encountered: core dump [ptmak()+191] [SIGSEGV]

Usually this problem is related with debug scructures.Today one of our developers was complaining with ora-031114: Not Connected to Oracle and when i checked the alert log i saw ORA-07445: exception encountered: core dump [ptmak()+191] [SIGSEGV] in alert log and this problem can occur if last time debug mode was on and compiled package before upgrading to database and retry to compile the same package after upgrading.What you should do is to check if package has debug flag or not.if it has debug flag then just disable it.Good luck.