ERROR: invalid byte sequence for encoding "UTF8": 0x00

All;

we are doing an oracle to Postgresql conversion, lots and lots of the
oracle columns throw this error:

ERROR: invalid byte sequence for encoding "UTF8": 0x00

CONTEXT: converting column [colname] for foreign table scan of
[tablename] row xxx

We are using the ora_fdw oracle foreign data wrapper extension to
perform the data conversion, we create the foreign tables via the
"IMPORT FOREIGN SCHEMA" option, then do an insert in [postgres_table]
select * from [ora_fdw_table]

I've tried a number of fixes but they all seem to replace the data for
ALL rows instead of just the broken ones.

For example:

select id, cname from ora_fdw_schema.cust_names

ERROR: invalid byte sequence for encoding "UTF8": 0x00

CONTEXT: converting column cname for foreign table scan of
ora_fdw_schema.cust_names, row 122

If I use replace then ALL rows are NULL:

select id, replace(cname,'',NULL)  from ora_fdw_schema.cust_names

    id    |         replace

---------+----------------------

1         |

2         |

3         |

4         |

5         |

6         |

7         |

Same thing if I use translate:

select id, translate(cname,'',NULL)  from ora_fdw_schema.cust_names

Help?

Thanks in advance