Replacing Firefox-esr with Firefox

I’d like to install the regularly updated version of Firefox.

A new installation of Debian was showing as using the stable long term supported Firefox ESR (extended support release) package.

The task was to remove the package firefox-esr and install the package firefox, or its installation equivalent.

To delete the currently installed package firefox-esr will be

apt remove firefox-esr

However, that can wait until the other package is all installed and shown to be working.

Yes, you can run both versions of Firefox.

To delete the stable version of Firefox and install in its place the I would prefer to use the more regularly updated version of Firefox.

For reference the initial content of the file /etc/apt/sources.list was:

deb http://mirror.ox.ac.uk/debian/ buster main
deb-src http://mirror.ox.ac.uk/debian/ buster main

To search for the installation package for Firefox, it will list all packages with a reference to firefox, use:

apt-cache search firefox

Comparing the new computer installation against an existing operational computer.

For the new computer configuration no Firefox packages were shown, but there were the equivalent language versions of firefox-esr, but on the already operational computer

The one which was already configured, there was a limited number of firefox-esr packages shown, with lots of language variations on the firefox package.

firefox - Mozilla Firefox web browser
firefox-l10n-ach - Acoli language package for Firefox
firefox-l10n-af - Afrikaans language package for Firefox
firefox-l10n-all - All language packages for Firefox (meta)
firefox-l10n-an - Aragonese language package for Firefox
firefox-l10n-ar - Arabic language package for Firefox
firefox-l10n-as - Assamese language package for Firefox
firefox-l10n-ast - Asturian language package for Firefox
firefox-l10n-az - Azerbaijani language package for Firefox
firefox-l10n-be - Belarusian language package for Firefox
: : :
firefox-l10n-sv-se - Swedish (Sweden) language package for Firefox
firefox-l10n-ta - Tamil language package for Firefox
firefox-l10n-te - Telugu language package for Firefox
firefox-l10n-th - Thai language package for Firefox
firefox-l10n-tr - Turkish language package for Firefox
firefox-l10n-uk - Ukrainian language package for Firefox
firefox-l10n-ur - Urdu language package for Firefox
firefox-l10n-uz - Uzbek language package for Firefox
firefox-l10n-vi - Vietnamese language package for Firefox
firefox-l10n-xh - Xhosa language package for Firefox
firefox-l10n-zh-cn - Chinese (China) language package for Firefox
firefox-l10n-zh-tw - Chinese (Taiwan) language package for Firefox
: : :
firefox-esr-l10n-be - Belarusian language package for Firefox ESR
firefox-esr-l10n-ia - Interlingua language package for Firefox ESR
firefox-esr-l10n-my - Burmese language package for Firefox ESR
firefox-esr-l10n-ne-np - Nepali (Nepal) language package for Firefox ESR
firefox-esr-l10n-oc - Occitan language package for Firefox ESR
firefox-esr-l10n-ur - Urdu language package for Firefox ESR

Can I simply install the firefox package then?

E: Package 'firefox' has no installation candidate

Should I use one of the language representations, as listed in  the search?

apt install firefox-l10n-uk

Once again it couldn’t find the package:

E: Package 'firefox-l10n-uk' has no installation candidate

I edited the file /etc/apt/sources.list, modifying the reference to buster to testing and added contrib non-frree, giving:

deb http://mirror.ox.ac.uk/debian/ testing main contrib non-free
deb-src http://mirror.ox.ac.uk/debian/ testing main contrib non-free

To reflect the change I action

apt update

Trying once more with the install and getting the now usual no installation candidate error.

I also replicated the reference to the testing distribution, adding two comparable lines for experimental.

As before I actioned an update and tried to do the installation. Another installation candidate error.

Looking at the Debian wiki page for Firefox it suggests using the unstable distribution.

I added this to the sources.list file:

deb http://mirror.ox.ac.uk/debian/ testing main contrib non-free
deb-src http://mirror.ox.ac.uk/debian/ testing main contrib non-free

deb http://mirror.ox.ac.uk/debian/ experimental main contrib non-free
deb-src http://mirror.ox.ac.uk/debian/ experimental main contrib non-free

deb http://mirror.ox.ac.uk/debian/ unstable main contrib non-free
deb-src http://mirror.ox.ac.uk/debian/ unstable main contrib non-free

Success! I now had the regularly update Firefox version installed.

Firefox as opposed to Firefox-esr can be installed on Debian via the repositories with a simple change to the sources.list file and acouple of command line actions.