Message Oracle SQL*Loader-00421 - error converting data

ERRORerror converting data
CAUSEThis message can be displayed as one of the reasons for rejecting a row. The sqlldr utility was attempting to convert data for the column from its datatype in the data file to the datatype for the column in the database. This message should be followed with another message describing the conversion error.
ACTIONCorrect the data in the data file so that it can be converted.