PG Admin error: pg_dump: aborting because of server version mismatch

If you are using linux you just need to remove the symlinks from the previous versions and point to the version that you are using like this:

locate pg_dump

sudo rm /usr/bin/pg_dump
sudo rm /usr/bin/pg_dumpall
sudo rm /usr/bin/pg_dropcluster
sudo ln -s /usr/lib/postgresql/9.3/bin/pg_dump /usr/bin/
sudo ln -s /usr/lib/postgresql/9.3/bin/pg_dumpall /usr/bin/
sudo ln -s /usr/lib/postgresql/9.3/bin/pg_restore /usr/bin/
sudo rm /usr/bin/pg_restore
sudo ln -s /usr/lib/postgresql/9.3/bin/pg_restore /usr/bin/