Oracle Database / Connections & Oracle Net
ORA-03113: preserve server evidence after an unexpected disconnect
An end-of-file communication error describes a broken session, not its root cause. The server process may have failed or the connection may have been interrupted.
Environment and inputs: Oracle Database 19c baseline · SQL*Plus-compatible SQL unless RMAN, DGMGRL, ADRCI or a host shell is specified. Check release, patch level, edition and container first.
Start with this diagnostic
Use the stated SQL, RMAN, DGMGRL or host shell and replace sample names with approved targets. DBA and V$ views need authorized catalog access in the correct container. Do not grant broad privileges for an example.
SELECT name, value FROM v$diag_info WHERE name IN ('Diag Trace','Diag Alert');Read the result
From a separate healthy authorized session, the query locates diagnostic directories for this instance. The client error alone does not identify the failing server component.
Resolve and verify
Correlate the disconnect time and process details with the alert log, trace files and network events. Preserve the complete error stack and involve Oracle Support for a server crash.
Operational precautions
Do not repeatedly restart the instance before collecting evidence. Diagnostic files can contain SQL text and sensitive values.