All Oracle Error Codes
Oracle DBA Forum
invalid format parameter
The format parameter passed to a UTL_PG conversion routine was invalid. The format parameter should have been built by a prior call to either MAKE_RAW_TO_NUMBER_FORMAT or MAKE_NUMBER_TO_RAW_FORMAT.
Check to be sure that the format parameter was built by MAKE_RAW_TO_NUMBER_FORMAT or MAKE_NUMBER_TO_RAW_FORMAT, and that it was not accidentally overwritten or modified by the PL/SQL procedure.