I initially followed instructions to install postgres and pgadmin4 from https://tecadmin.net/install-pgadmin4-on-ubuntu/ successfully.
I seemed to be able to get to the site at http://localhost/pgadmin4 but couldn't login.
After a few attempts to reset the pgadmin4 user/password. I thought okay I'll just remove/reinstall it with:
sudo apt-get autoremove pgadmin4 pgadmin4-apache2
When I re-installed I am not reprompted for the pgadmin user info AND the url which previously worked now gives a 404 not found.
I have restarted the server.
I have rebooted after reinstallation.
I did a recursive search for pgadmin to remove any trace of it from my pc before reinstalling on machine.
I've looked in /etc/apache2 sites-enable, mods-enabled, config-enabled etc... to see if there are traces of the previous install.
I've searched here and stackoverflow and the web generally but not having much success.