Fatal Error: Attempt to setIsNull() on the accessor interfacing to non-nullable field "column_name".

As evident this error can occur when you are trying to assign a NULL value to a NOT NULLABLE column. But this can be a little tricky sometimes.

Like if you use trim(col_name) where col_name is a not nullable column. Still it can have a NULL value as trim(Blank Spaces) in oracle gives NULL.

So, if you are using a trim in the query and the column is defined NOT NULL, beware that it can give the above error in case blank values(which are in fact NOT NULL) come in that

Column.

You can resolve it  by defining the column as NOT NULL, or remove the trim from the query and use the trim in a transformer.