ORA-03113: end-of-file on communication channel

The connection between the client and the server process was cut unexpectedly. The cause can be on either side: a server process that died, a network device closing idle connections, or a database that went down. Start with the alert log.

What ORA-03113 means

The client was waiting for the server and the connection simply ended. The message says that something broke, not what. If the server process crashed, the alert log usually has an ORA-00600 or ORA-07445 at the same moment. If the alert log is clean, look at the network: firewalls often drop connections that stay idle.

Common causes of ORA-03113

The server process crashed, often together with ORA-00600 or ORA-07445.
A firewall or load balancer dropping idle connections.
A session killed by an administrator, or the instance shutting down.
An unstable network, VPN or connection through a proxy.

How to fix ORA-03113

Find the time of the error in the alert log and look for ORA-00600, ORA-07445 or a shutdown.
If the database is healthy, suspect the network. Set SQLNET.EXPIRE_TIME in the server’s sqlnet.ora so that idle connections are kept alive.
Check the idle timeouts of firewalls and VPNs between client and server.
If one statement always triggers it, treat it as a crash: check the trace file and My Oracle Support.

ORA-03113 example

Keep idle connections alive (server-side sqlnet.ora, minutes):

SQLNET.EXPIRE_TIME = 10

Look for errors around that moment:

adrci> SHOW ALERT -TAIL 100
adrci> SHOW INCIDENT -MODE BRIEF

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Oracle documentation for ORA-03113. Oracle is a registered trademark of Oracle Corporation. SQLlightspeed is not affiliated with Oracle.