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### Can I run two different versions or multiple instances at once?

Yes. However you'll need to use different profiles for each instance you open or multiple copies of the same profile to do so.

Open your operating system's command shell and type the following lines in bold.

Windows:

C:\>cd C:\Program Files\Mozilla Firefox
C:\Program Files\Mozilla Firefox>set MOZ_NO_REMOTE=1
C:\Program Files\Mozilla Firefox>firefox.exe -p
-or-
C:\Program Files\Mozilla Firefox>firefox.exe -Profile "C:\Path\to\profile"

Linux & OSX:

$cd /firefox/location$ export MOZ_NO_REMOTE=1
$./firefox -p -or-$ ./firefox -Profile "/path/to/profile"

To simplify the process, you can create either a batch file or shell script to quickly open multiple instances of Firefox at once. Just remember that each instance must not share its profile with any of the other active instances. Removing the profile lock file while Firefox is running is not recommended.

Feedback received on this FAQ entry:
• Firefox Portable (portableapps.com) can handle this automagically for you. You just have to set AllowMultipleInstances to 'true' in its .ini file; this merely sets the -no-remote and -profile flags for startup. Since this will cause the PAF launcher to terminate after starting Firefox, you wouldn't want to do this with the one(s) you install into the PAc menu/platform. You should only do it with the ones you install "standalone", being aware that it removes true portability for that instance. However, this will allow you to run as many instances as you want for as many different releases as you want, all isolated one from the other.

2015-02-09 17:44:07 (NotTheMama )

by Ryan F edited by MacGyver
last modified: 2005-10-06 08:28:17