ORA-01843: not a valid month

ORA-01843 is an error message in Oracle database that indicates the date format is not valid. This error typically occurs when you try to insert or update a date value using an invalid format. To resolve this error, you need to ensure that the date value is in the correct format, which is usually either in "DD-MON-YYYY" or "DD/MM/YYYY" format. You can also check the NLS_DATE_FORMAT setting to ensure that it matches the date format you are using in your SQL statement.