Firefox Community Forum

Hi everybody. Thanks in advance for your help.

I'm on Win 11 23H2, and I'm currently running Firefox 88.0.1 x64. Why? Because it's heavily customized to suit my needs. Some examples:

• Extensions (e.g. Classic Theme Restorer)
• userChrome.css and userContent.css customizations ( https://github.com/aris-t2/customcssforfx ), which include tabs on bottom (mandatory for me), tab height/width, and many other things.

I decided a long time ago to stay with v88 because every new Firefox update was breaking things that I needed, and I got tired to spend hours with every new update. If only Firefox devs could find a way to NOT break user customizations with every new update...

Of course I'd like to update my Firefox to the latest version. But I know that it's going to be a nuclear bomb. I already made a test. First I made a backup of my profile folder, then I just updated Firefox. Suffice to say that not only all my customizations disappeared : even my tabs disappeared, and I have dozens of them. So I had to uninstall everything, copy back my previously saved profile folder (because of course it had been modified by the latest version), and reinstall Firefox 88.0.1.

So here's my plan and my question. Would it be possible to have two different Firefox installs (not portable I guess), with two different profiles, running at the same time?

• Here's how I see it:
• Download Firefox latest version
• Close Firefox 88
• Move profile folder away from AppData\Roaming\Mozilla\Firefox\Profiles, so Firefox latest version can't find it
• Move Firefox folder (the one within Program Files) so hopefully Firefox latest version can't find it
• Install Firefox latest version (it then creates a new user profile folder)
• Start Firefox latest version
• Move back the old Firefox folder to Program Files (so there will be two different Firefox folders, e.g. "Mozilla Firefox 88" and "Mozilla Firefox")
• Move back the old profile folder to AppData\Roaming\Mozilla\Firefox\Profiles (so there will be two different user profile folders)
• Start Firefox 88

Would that work, or am I missing something?

If it worked, then I could keep working on Firefox 88, while gradually customizing Firefox latest version until it's ready to take over.

Thanks in advance for your insights!