ORA-01856: BC/B.C. or AD/A.D. required
Cause: A date specification contained a BC/AD format code but a valid BC/AD indicator was not specified. If one of the BC/AD format codes, BC/AD or B.C./A.D., is specified in a date format, the date must include BC/B.C. or AD/A.D.
Action: Specify the BC/AD indicator in the date using the correct format.