pgAdmin is a free software used for PostgreSQL database management.
As you may know, starting with pgAdmin 4, which is a WebApp, the former pgAdmin3 loses support for managing PostgreSQL servers version greater than 9.5. The latest pgAdmin3 official release is 1.22 and can still be used for PostgreSQL 10, 11, 12, 13, but with some missing features (ex failures to display the list of stored functions) and some strange errors.
But, thanks to the Open Source world, the pgAdmin3 it's not dead yet. It's quite alive.
Compile and install a patched pgAdmin 3 with support for PostgreSQL 10,11,12,13 - Ubuntu Desktop 20.04 LTS
An open-source version of a patched pgAdmin3 can be found here https://github.com/allentc/pgadmin3-lts.git, a repo that we will use to compile and install pgAdmin3-LTS (v1.23b,BigSQL,forked) on our Ubuntu Desktop machine.
sudo apt install postgresql-server-dev-12 libwxgtk-media3.0-gtk3-dev git clone https://github.com/allentc/pgadmin3-lts.git cd pgadmin3-lts bash bootstrap ./configure --prefix=/usr/local --with-pgsql=/usr/lib/postgresql/12 --with-libgcrypt CFLAGS=-fPIC CXXFLAGS=-fPIC --with-wx-version=3.0 make sudo make install
If everything worked as expected, create a Gnome application launcher for quick access:
sudo nano /usr/share/applications/pgadmin3.desktop with bellow content, save it (Ctrl+X) and reload Gnome afterall (Alt+F2, r)
[Desktop Entry] Name=pgAdmin3 Exec=pgadmin3 Icon=/var/lib/app-info/icons/ubuntu-focal-universe/64x64/pgadmin3_pgadmin3.png Type=Application
Install a patched pgAdmin 3 with support for PostgreSQL 10,11,12,13 - Windows and other Debian based Linux distros
For those who are not comfortable compiling software (yes, the aforementioned repo can be used to compile pgAdmin3 not only for Linux but also for Windows and macOS), I've found Victor Spirin from http://mobile-n.com who is keeping alive up to date pgAdmin3 installers, for Windows and Debian, here: https://vvs.ru/pg/index-en.html. Thank you, Victor.
That's it, pgAdmin3 at least till the EOL of PostgreSQL 13