Eoghan Murray <eoghanomurray(at)gmail(dot)com> writes:
> How can I migrate a database from 8.4 to 8.3?
The only way is to dump to text (no -Fc or -Ft) with 8.4's pg_dump,
and then manually edit the file until 8.3 will take it.
> 8.3: pg_restore: [archiver] input file does not appear to be a
> valid archive
It's possible here that your only mistake was using -Fc. That format
isn't necessarily backwards-compatible.
regards, tom lane