Running multiple versions of Firefox simultaneously
29 June, 2011 § 14 Comments
Working on a browser brings with it an interesting set of problems, one of which deals with the fact that much software research relies on looking at websites. In order to test a change, normally the browser would have to be shut down before it is recompiled. This can make reading documentation much more difficult.
Fortunately, Firefox has a way to run multiple versions of the browser at the same time. As you may (or may not) already know, there are four versions of Firefox produced by Mozilla: Release, Beta, Aurora, and Nightly.
I use one of the Release/Beta/Aurora builds for most of my browsing, while I use Nightly to test out changes that others may have checked in within the past couple of days. The fifth build of Firefox that I use is one that I compile on my local machine.
To do this, I have modified the shortcut to Firefox to add specific profiles for each build of Firefox. Simply update the shortcut target to "../firefox.exe" -P "profileName" -no-remote
The command line switch will start Firefox using the given profile name and the -no-remote switch tells Firefox to allow multiple versions of Firefox to run simultaneously.
JAWS 
Interesting.Does this methord just work for firefox?
I try other browsers like Avant browser.chrome that I ‘m using.
I’ll back to post the result.
I would be surprised if the same command line arguments work for other browsers, but it just might. I’m interested to hear your results 🙂
Oh yeah I hit that issue! I hit it when I create little add-ins and I need to close the app. That’s cool how Firefox has a solution for this! I would otherwise just use a different browser for the documentation while creating the add-in.
Of course, if you build your addons with the new Add-On SDK, then your addons will be “restartless”, meaning you won’t have to restart the browser to run them 🙂
Will this work with different releases. i.e. I need to run 3.6 so I can use roboform but I also want to run the latest version currently 10.
Yeah, this will work with different releases.
Doesn’t work. Keeps telling me “another instance of Firefox is also running”.
I didn’t previously set up a second profile, maybe that’s the reason.
Yeah, you’ll have to set up a second profile first. To do that, run firefox.exe -ProfileManager -no-remote
This produces no effect whatsoever, except to start up Firefox.
Hmmm… I must be missing something in my post then. I’ll double check to see if I missed any steps. For each instance of Firefox you will need to the use the -no-remote command line flag.
I’m glad I found this old thread. This was exactly what I needed. I had already had 2 different profiles made for 2 different versions of Firefox, but didn’t like having to exit out of each one to get to the different versions. Now, I can run both versions at the same time! Great fix
How can run this command in Ubuntu Linux 13.10? is the same issue run the 2 browsers at the same time?
You can run this command the same on Ubuntu via the command line as you would run it on Windows. `firefox.exe -p profileName -no-remote`
Yes thanks! I can run it and Im playuing with the new version, very nice works better than FFv 25 but…. I cant see the bottom bar I think its deleted? what happen with all the extensions running in that position?