BUG #16284: Pg_dump is not working and PostgreSQL APP no longer available

The following bug has been logged on the website:

Bug reference:      16284
Logged by:          Tony Ryf
Email address:      tony.ryf@planetwerks.ch
PostgreSQL version: 11.4
Operating system:   Qnap 4.4.1
Description:

Hi 

I wanted to dump the Database with following command on Qnap 4.4.1 with
PostgreSQL 11.4.1 (this command works on Qnap 4.4.1 with PostgreSQL 9.3.13.3
).

./pg_dump -U postgres -h localhost -p 5432 -f
/share/Postgres-Backup/postgres-davinci-di.sql filmerei21
Password: 

pg_dump: server version: 11.4 (Debian 11.4-1.pgdg90+1); pg_dump version:
9.3.13
pg_dump: aborting because of server version mismatch

So how can I backup the Database? We also realized that the PostgreSQL App
is no longer available on Qnap System. Qnap Support advised us to contact
you. 

We have two QNAP Server running both with QNAP 4.4.1 one with PostgreSQL
11.4.1 and the other with PostgreSQL 9.3.13. Both App were downloaded from
the Qnap store.

Thanks for your support and advice how to proceed when the app is no longer
available on Qnap.

Tony Ryf