I connect from Toad to my database. When leave the session idle I would get
ORA-12571: TNS:packet writer failure
followed by access violations.
The database halts or the current session is terminated with the error: ORA-12571: TNS:packet writer failure
The error may be observed by a session currently using the database and will appear in the alert log file.
Possible causes and remedies:
1. With Oracle 8.0.4 onwards, this error may indicate that the database is in the process of being shut down.
2. This error has been observed when there was a loose cable connection to the SCSI disk array (on an Oracle Parallel Server system). Related errors were also subsequently noted in the NT event log.
If this is the cause then the remedy is to check all the cable connections. Do this by hand rather then visually, since a cable not being firmly in place could cause the problem.
3. This problem can also be caused by an IP address conflict (Oracle 9.0.1). Windows will normally log an IP conflict in the event log and show a pop up alert - but only if it detects the conflict.
Check that no other computer on the network has the same IP address as the machine on which the problem has been reported.
4. The error maybe caused when reinstalling Oracle 22.214.171.124 on Windows 2000. The solution was to edit the sqlnet.ora file (locations on different systems will vary, but in this case was at D:/Data/ora920/network/admin/sqlnet.ora) and change the line: