"ORA-03135: connection lost contact" when inserting large file

This can be a complicated issue with many different possible causes and solutions. Start here:

http://www.dba-oracle.com/t_ora_03135_connection_lost_contact.htm

Answer: The oerr utility shows this for the ORA-03135 error:

ORA-03135: connection lost contact

Cause: 1) Server unexpectedly terminated or was forced to terminate. or 2) Server timed out the connection.

Action: 1) Check if the server session was terminated. 2) Check if the timeout parameters are set properly in sqlnet.ora.

The ORA-03135 error is common when connecting remotely when a firewall terminates the connection.

One solution for the ORA-03135 error is to increase the value of the sqlnet.ora expire_time parameter in the sqlnet.ora file or to check for a expire parameter in a SQL*Plus profile.

To diagnose the ORA-03135 error, start by checking to see if the OS PID still exists, using the ps –ef|grep syntax.

Check to see if there is a Network Address Translation (NAT) between the client and server

In Windows, check to see if a Windows firewall is checking for your local connections:

Windows XP -> Control panel -> security -> Tab "Advanced"

Also, setting the parameters sqlnet.inbound_connect_timeout and inbound_connect_timeout_listenername to 0 can stop the ORA-03135 error.

Also as above, check the database alert log for errors occurring at the same time as the connection dropping. Sometimes it can be caused by an ora-600 or ora-7445, for example. It shouldn't appear in the listener log as you only get this error after handshaking has been completed.

This situation generally caused by disconnected/stale connection is taken from connection pool. If you get this exception after Pooling=false, most probably firewall blocks the connection because of tcp idle timeout. Ensure tcp idle timeout value is bigger than expected command execution time