Yes, I should know it. thank you.
There are a few sentences about pg_dump syntax compatibility from
postgresql documentation:
Because pg_dump is used to transfer data to newer versions of
PostgreSQL, the output of pg_dump can be expected to load into
PostgreSQL server versions newer than pg_dump's version. pg_dump can
also dump from PostgreSQL servers older than its own version.
(Currently, servers back to version 7.0 are supported.) However, pg_dump
cannot dump from PostgreSQL servers newer than its own major version; it
will refuse to even try, rather than risk making an invalid dump. Also,
it is not guaranteed that pg_dump's output can be loaded into a server
of an older major version — not even if the dump was taken from a server
of that version. Loading a dump file into an older server may require
manual editing of the dump file to remove syntax not understood by the
older server.
>
> pgAdmin doesn't create the dump file - it just calls pg_dump. Make
> sure you have the correct version of pg_dump in the directory pointed
> to by the PG Bin Path setting on File -> Options dialog.
>