Tech Tip: Run Firefox 3.6 and Firefox 4 Beta Simultaneously

By Julio Franco · 14 replies
Jul 28, 2010
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  1. It's been a few weeks since Mozilla released the first beta of Firefox 4, a major overhaul of the world's second-most used web browser. While we're pleased to report that the performance issues plaguing earlier versions seem to be gone, the latest build isn't flawless – but what software is, let alone in beta stage?

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    Please leave your feedback here.
  2. Well, I've got a less troublesome way to run to different instances of Firefox. Just use the portable (4.0 beta 2) version along the official one as explained in the following post and you should be good to go ;-)
  3. You can simplify this by only creating the one new profile and applying the "-p PROFILE -no-remote" command line option to only one of your FireFox shortcuts.

    If for example you want to keep FireFox 3.6 as your default browser you can leave it to use the existing 'default' profile, create a new "FireFox4" profile and apply the changes only to the FireFox 4.0 Beta 2 shortcut(s). If you want to use FireFox 4.0 Beta 2 as your default browser, and keep FireFox 3.6 as a backup, do the opposite.

    When adding the changes to both icons, I had problems with some programs not being able to open tabs in an existing FireFox window, instead I would receive the infamous error about having to close existing FireFox windows.
  4. does this trick only work for win7? how about xp?
  5. Matthew

    Matthew TechSpot Staff Posts: 5,332   +101

    Indeed. As noted in the article: "All you have to do is create a new profile for Firefox 4, but you may want to rename your existing profile to keep things tidy."

    For what it's worth, I had no trouble in testing. Oh, and the general workaround should apply to any OS.
  6. Firefox had been my default browser. Although I still use it, I had to give it up as my default browser as it will not save pages properly, nor will it properly print to PDF. In the latter case it not only truncates the name leaving one with little extra dots to delete and name to complete, it also truncates the PDF file itself. I would only go to the trouble of trying to use both versions if the new beta would finally save properly. The last beta 4x version that I tried, still does not fix this problem. A shame really as any other browser I have tried, e.g., Chrome, easily accomplishes these tasks. When I get my main system processor changed, which should be in time for the new beta release I will give it a try, but I imagine I will again be disappointed. I HOPE I am wrong!
  7. I too had problems with FF printing to a PDF. I tried several programs with no success but I stumbled upon PDF995 which is free and it works great. There's also an add-on call Print to PDF that works well too.
  8. Usually I'll see an article like this that tells you how to run two versions of the same browser on your computer at once. Then you try it and you can't make it work no matter what you try. This is the first one that worked for me. I'm running Windows 7 home Premium 64-bit on an Asus G72 gamers laptop.

    Thank you! :)
  9. Matthew

    Matthew TechSpot Staff Posts: 5,332   +101

    :) You're welcome.
  10. This is not reliable. Both browsers cause each other several problems.
  11. Just for other novices like me.
    Concerning adding ( -p PROFILE -no-remote ) to the end of the
    Taget: "C:\Program Files (x86)\Mozilla Firefox 4.0 Beta 7\firefox.exe"
    I finally realized that there had to be a (space) at the end before it was added.
  12. Matthew, I did all that you said, in the order that you stated and now the only way I can open up 3.6.13, is by using
    C:\Program Files (x86)\Mozilla Firefox\firefox.exe -p -no-remote in the run command and then selecting “Firefox3” → Start Firefox.

    Neither the Start Menu, Task Bar, All Programs nor Desktop shortcuts work. Each pair opens up 4.0.
    I have even tried unpinning then re-pinning as well as adding shortcuts to the desktop from All Programs. Still the same situation.

    Doing the -p -no-remote thing at least gives me a way to open 3.6.13.

    Anyone got any ideas?????
  13. Great article tried it on Firefox 3.6.13 and Firefox 4.0b9pre today and it worked like a charm :D No more wasted time opening and closing various versions of Firefox :)
  14. Arg. This is really frustrating. This article is missing something important and I don't know what it is. If I create a new profile, I just have two profiles pointing to firefox beta 4. How do I point one of them to the old version of Firefox. Creating a new profile only creates a new profile! How do I point it at the right version of firefox!?
  15. This process seems straightforward, but it doesn't explain whether I am supposed to install v 4 in a new directory, or in the default directory, which, to me seems like it will overwrite 3.6. I'm on XP.

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