Oracle Database / SQL & PL/SQL Errors
ORA-01843: diagnose a date string with an invalid month
A date literal can work in one session and fail in another because language or date-format assumptions differ. Capture the affected session's NLS settings.
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 parameter, value FROM nls_session_parameters WHERE parameter IN ('NLS_DATE_FORMAT','NLS_DATE_LANGUAGE');Read the result
The values describe the current session and may differ from the application's pooled session. They explain implicit conversion assumptions, not the intended business format.
Resolve and verify
Use typed date binds or an explicit matching format model at the application boundary. Test representative localized input and validate rejected values clearly.
Operational precautions
Do not globally change NLS settings to compensate for one ambiguous input format.