All Oracle Error CodesOracle DBA Forum

PCB-00004:

UNSAFE_NULL=YES must be used with DBMS=V7 or V8 and MODE=ORACLE
Cause: The option UNSAFE_NULL=YES has been used with DBMS=V6 or DBMS=NATIVE (the default) or has been used with MODE=ANSI/ANSI14/ANSI13.
Action: Use DBMS=V7 or V8 and MODE=ORACLE (the default) when using UNSAFE_NULL=YES or do not use UNSAFE_NULL=YES.