Using older versions

[MMikeJBenN27]

Why am I barred from using an older version of FireFox?  My computer is not new, and the latest version of FireFox is just too much for it.  It is my computer, so I should be able to use the version of FireFox that I want, not what somebody else with lots of money says I should use.  What gives?

[Agentvirtuel]

Hello

Firefox
Release notes https://www.mozilla.org/en-US/firefox/releases
Calendar https://whattrainisitnow.com/calendar

Index of /pub/firefox/releases
https://ftp.mozilla.org/pub/firefox/releases/
Or
Index of /pub/firefox/releases
https://archive.mozilla.org/pub/firefox/releases/

What happens to my profile if I downgrade to a previous version of Firefox?
https://support.mozilla.org/en-US/kb/dedicated-profiles-firefox-installation#w_what-happens-to-my-pr...

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You've launched an older version of Firefox

Note: Downgrade protection can be overridden by launching Firefox through the command line with the --allow-downgrade parameter.

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firefox.exe --allow-downgrade
Command above to be executed only 1 time
Firefox will start
Then stop Firefox
Then start Firefox as usual

For information purposes other alternative
Dedicated profiles per Firefox installation
https://support.mozilla.org/en-US/kb/dedicated-profiles-firefox-installation

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Some users have multiple installations of Firefox, each in separate program folders. Firefox uses a dedicated profile for each installation of Firefox, including Nightly, Beta, Developer Edition and Extended Support Release (ESR) installations. This makes Firefox more stable when switching between installations on the same computer, and also allows you to run different Firefox installations at the same time.

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Prerequisite to installation location, for example and Windows

64-bit
Create Mozilla Firefox Esr installation folder in C:\Program Files
C:\Program Files\Mozilla Firefox Esr
Install Firefox Esr in C:\Program Files\Mozilla Firefox Esr

32-bit
Create Mozilla Firefox Esr installation folder in C:\Program Files (x86)
C:\Program Files (x86)\Mozilla Firefox Esr
Install Firefox Esr in C:\Program Files (x86)\Mozilla Firefox Esr

Custom installation of Firefox on Windows
https://support.mozilla.org/en-US/kb/custom-installation-firefox-on-windows

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A Custom setup lets you choose the folder where Firefox program files will be installed

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Illustration
Firefox Nightly Bêta Release
https://drive.google.com/file/d/19836pv4BJhXL-n9EBA3CoyIj7CzRvjP7/view?usp=sharing
You can also download the animation if you wish

Other illustration different Firefox installations at the same time
https://connect.mozilla.org/t5/discussions/121-0-1-useless-quot-xyz-is-slowing-down-firefox-quot-lin...

DisableAppUpdate other information
Take a look https://connect.mozilla.org/t5/discussions/forced-restart/m-p/48809/highlight/true#M17509

[jscher2000]

Nobody is barred from running an older version. However, for security reasons, Firefox will try to update itself as long as your system is compatible with the current release.

https://support.mozilla.org/en-US/kb/install-older-version-firefox