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I often get "ORA-03113 "end-of-file on communication channel" under all sorts of conditions. What causes it and how do I stop it?

Author's name: Dave Wotton Author's Email: dwotton@clara.co.uk	Date written: 11th October 2001 Oracle version(s): 8.1.6 onwards
This problem can occur under a variety of conditions. One very common situation is when creating an initial database as part of the Oracle installation. It can often be accompanied by an ORA-01034: "ORACLE not available" message if the cause of the problem has also crashed the database.

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ORA-3113 "end-of-file on communication channel" is a catch-all error message which simply means that the foreground oracle client process (svrmgrl, sqlplus, RMAN, Oracle Forms etc.) has lost contact with its background shadow process.

Unfortunately there are many causes of this. Network glitches were clearly the cause that the Oracle developers had in mind when they phrased the error message, but anything which causes the shadow process to crash will cause this error to be reported.

This message may also be accompanied by other messages, either displayed on the screen or in log files. If the background process which has crashed is one of the essential Oracle servers processes (PMON, SMON, DBWR etc.) you may also get an ORA-1034 ORACLE not available error message. Looking in the alert log or looking through any trace files in your background_dump_dest may help diagnose the problem.

Common causes are:

Incompatible values of the init.ora parameter processes and the kernel shared memory and semaphore parameters
This is a very frequent cause because the default installation of Oracle sets up incompatible values!
Oracle executables need relinking
shared_pool_size too small.
timed_statistics=true.
This is probably version and path-level specific. But at least one version of Oracle benefits drom switching off timed_statistics.
a datafile extended over 2Gb in size.
Create table as select .... where there was an invalid procedure or function called from a trigger defined on the table we were selecting from.

Further reading: All these causes, (and potentially others), are described in more detail on my (Dave Wotton) web-page: Causes of ORA-3113

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