"Unrecognized configuration parameter: qreplace_function" trying to backup a database
You have not used  PostgreSQL. You are using  PostgresPlus created by EnterpriseDB.

The parameter qreplace_funtion is mentioned in EnterpriseDB's document (page 21). I guess this is a typical privilege problem.

OR, if you use PostgreSQL but run PostgrePlus's pg_dump, try original PostgreSQL's pg_dump.