oracle error messages

Oracle/PLSQL: ORA-01843

Learn the cause and how to resolve the ORA-01843 error message in Oracle.


When you encounter an ORA-01843 error, the following error message will appear:

  • ORA-01843: not a valid month


You entered a date, but the month portion of the date was not a valid month.


The option(s) to resolve this Oracle error are:

Option #1

Re-enter the date value using either a MONTH format mask.

The valid values for month are:

  • January
  • February
  • March
  • April
  • May
  • June
  • July
  • August
  • September
  • October
  • November
  • December

Or you could use the MON format mask and use one of the following values:

  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec

If all else fails, you may want to consider using the TO_DATE function and specifying the date format mask.