Solve error = 12571

FATAL ERROR IN TWO-TASK SERVER: error = 12571Subject: FATAL ERROR IN TWO-TASK SERVER: error = 12571 Found in Alert File Doc ID: Note:164839.1 Type: PROBLEM Last Revision Date: 18-OCT-2007 Status: PUBLISHED

fact: Oracle Server - Enterprise Editionsymptom: Errors appear in alert file symptom: FATAL ERROR IN TWO-TASK SERVER:symptom: ERROR = 12571symptom: trace file generatedsymptom: Database operations continue successfullycause: The most common cause for the above error is an ungraceful disconnection of a session from the oracle db while the db is currently running a dml statement issued by that session. The error is recorded when oracle attempts to reply back to the session with the results of the dml and cannot access the session. Overall database operations are usually not affected.
An ungraceful disconnection could cause by but is not limited to any of the following:- the client machine crashed- the network connection crashed- the user exited the session improperly (not issuing the 'exit' command) - the user application allows the user to exit the application without properly terminating the session.
The above can cause problems with corrupted rollback segments if occurring on a regular basis and is not addressed. This would require db recovery and possibly a db rebuild (not a light matter)
PMON will usually rollback most transactions in the rollback segments for a session if it finds that the session has been ungracefully disconnected, but there is always a chance that it cannot and this will lead to rollback segment corruption.