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How do you run Firefox 52 and 60 at the same time? Old technology requires Firefox 52 to access, 60 does not work, so I need to run both.

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  • Last reply by jscher2000

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I need to run Firefox 52 and 60 concurrently, since new sites don't need the legacy support and old technology does not work with the new browsers, their security assumptions, and lack of java or flash support.

I'm fully aware of technology deprecating, so I don't want pontification about support for Java or flash, that's not relevant.

How do you run both Firefox 52 and Firefox 60, concurrently, using different profiles, installed to different folders, on the same Windows system?

Currently, Firefox will only run one instance, which is worrying, because that indicates that there are active dependencies which may indicate a lack proper process separation.

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This is a little complicated.

(1) Coexisting installs

When Firefox 57 first launched, I installed the 64-bit version under its default path:

C:\Program Files\Mozilla Firefox\

Then I installed the 32-bit version of Firefox 52 ESR under a custom path:

C:\Program Files (x86)\Mozilla Firefox ESR\

(2) Separate Profiles

Versions of Firefox this far apart do not share well, and if you share data, you can't run them simultaneously. You will need to create separate profiles and make sure you never open an old one with a new Firefox. Lots of backups are recommended.

(3) Customized Shortcuts

You can specify you want a particular profile by adding the profile name to your shortcut. You also can set the shortcut to display the Profile Manager so you can select the one you want. It's useful to indicate the Firefox 52 profiles with a customized name.

Example Target paths in shortcuts:

  • Normal shortcut to run current Firefox (64-bit):
    "C:\Program Files\Mozilla Firefox\firefox.exe" -P "MyQuantumProfile"
  • Shortcut to simultaneously launch current Firefox (64-bit) into the profile manager to select a different profile folder:
    "C:\Program Files\Mozilla Firefox\firefox.exe" -P -no-remote
  • Shortcut to simultaneously launch Firefox 52 ESR (32-bit) with current Firefox in my ancient profile:
    "C:\Program Files (x86)\Mozilla Firefox ESR\firefox.exe" -P "jscher2000" -no-remote
  • Shortcut to simultaneously launch Firefox 52 ESR (32-bit) into the profile manager to select a different profile folder:
    "C:\Program Files (x86)\Mozilla Firefox ESR\firefox.exe" -P -no-remote

(4) External Link

It's a little unpredictable what will happen if no instances of Firefox are running and you try to launch an external link. I'll usually get a Profile Manager popping up and have no idea which version of Firefox it will be, so I try to make sure Firefox is always running.

(5) More Backups

No matter how careful you are, it seems, inevitably you'll mess up and then need to restore your profile data back to how it was.