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Oracle Troubleshooting

ORA-01843: not a valid month

Symptom:

When performing some SQL on a table the following error is returned:

ORA-01843: not a valid month

Cause:

This error means that a date was used in the SQL but that Oracle did not consider the month to be a valid month.

Remedy:

• If the month was expressed as a digit then try expressing it in full, i.e. January, February, etc or as a recognised abbreviation Jan, Feb, etc
• Consider changing the session's date format, e.g.:

  alter session set nls_date_format='DD/MM/YYYY';

  However, be aware that this may have an undesirable knock-on affect for any other SQL.