- Can you ensure whether all the services (Database & Listener) are up running ?
- Is it failing consistently ?
- Any error in the Alert.log
Can you check if there is any usage of DB links and if yes then are those DB links working ?
Please increase processes to 1000 and restart the DB.
MSCPLD Loader Worker With Direct Load Option Fails With Sql*Loader-704: Internal Error: Ulconnect: Ociserverattach  ORA-12537: TNS:connection closed (Doc ID 1142930.1)