Be forewarned that if you decide to un-install the 3.0 version using the un-installer and you select the box labeled "Remove my Firefox / Minefield personal data and customizations", you will be removing all personal data and customizations for every version of Firefox that you now have installed! Please be careful with that feature, it won't remove just the 3.0 data, you'll lose everything.
1) Backup your 2.0.0.x Profile before doing anything! (just in case)
a - Backup your profile manually - http://kb.mozillazine.org/Profile_backu ... he_profile
b - MozBackup - Backup tool for Firefox and Thunderbird - http://mozbackup.jasnapaka.com/
c - Firefox Extension Backup Extension - FEBE - https://addons.mozilla.org/firefox/2109/
Compact Library Extension Organizer - CLEO - https://addons.mozilla.org/en-US/firefox/addon/2942
2) Create a new Profile with 2.0.0.14 (or whatever you have now), but don't launch any version with that new Profile, yet. After creating the new Profile and being returned the to the Choose User Profile dialog box, click Exit.
http://kb.mozillazine.org/Creating_a_ne ... on_Windows
http://kb.mozillazine.org/Profile_Manager#Linux
http://kb.mozillazine.org/Profile_Manager#Mac_OS_X
3) Install 3.0 using the Custom Installation option if you're using an installer version, but don't launch it at the end of the installation process. On the last Installation window un-check the box that says Launch Mozilla Firefox 3.0 /Minefield now, then click Finish.
4) Go to the new desktop icon for 3.0 and Right-click > Properties, on the Target: line add the following:
space hyphen P space profileName
Sorry the screen shots don't match, I'm working on two different PC's with two different OS's - W2K & WinXP.
The -no-remote Argument is so that you can launch Firefox when another version is already running - see #8.
Note: Some OS's (Linux) may need -profilemanager instead of -P - thanks Äkiidoll
Click Apply, then close the Properties box.
5) Now you can launch 3.0 with its' own Profile with the desktop icon you just modified.
Additional steps you may want to do:
6) Copy user files from old 2.0.0.x profile to the new profile.
http://kb.mozillazine.org/Migrating_set ... ew_profile
Read this if you have the old signons.txt file:
http://kb.mozillazine.org/Signons.txt
7) Install either the Nightly Tester Tools extension - http://www.oxymoronical.com/web/firefox/nightly -
or Mr.Tech's Local Install extension - https://addons.mozilla.org/en-US/firefox/addon/421 -
to "override compatibility" for older extensions not yet updated for 3.0 Beta.
OR
in about:config = Right-click and select New > Boolean - extensions.checkCompatibility and set to false
Note: Either of those extensions or the new preference will allow older extensions to be installed, but those extensions won't necessarily work correctly, so YMMV.
You can override the need for secure update URL's (new to 3.0), which can prevent installation of some older extensions like this:
in about:config = Right-click and select New > Boolean - extensions.checkUpdateSecurity and set to false
8) Want to be able to have both 2.0.0.x and 3.0 running at the same time?
A Command Line argument for both Firefox 2.0 and Minefield/ 3.0 to 'invoke' the MOZ_NO_REMOTE Environment Variable is -no-remote .
As shown above.
Additional info from Vectorspace, edited by Ed:
9) Make sure that whichever version is set as your Default browser, that the corresponding Profile is the profile selected by default in Profile Manager; IOW, it is "illuminated" when you run the Profile Manager. (You can also inspect the profiles.ini file, that it shows Default=1 for that particular Profile - profiles.ini is a text file, use Notepad or other text program to view, and edit if you are courageous.)
This is to make sure that whenever Firefox is started from another app (like link in e-mail program) which launches the Default browser, that your Default browser is launched with the corresponding (correct) profile. [If you screw this up and run 3.0 with the 2.0.0.x Profile, that Profile will get b0rked, in which case your backup will be needed.]
If you are using an "installer" build of Minefield this is important for you. Zip-archive builds don't write to the Registry.
10) The version launched from going Start > Run and typing firefox.exe is the version most recently installed, and will also launch with the Default profile. If install order is 2.0 then 3.0 beta, 3.0 beta will be launched through this with the Default Profile. If 2.0 is default and 3.0's profile is default, running Firefox like this will start 3.0 with 2.0's profile. IOW, it is probably best using 3.0 as your Default browser, with the new Profile as the Default Profile; unless you modify the Registry key or re-install 2.0.0..x so it is the newest installation!
You can control which version is launched in this manner using the path to firefox.exe in this registry key:
HKEY_LOCAL_MACHINE > Software > Microsoft > Windows > CurrentVersion > App Paths > firefox.exe
Or, reinstall whichever version is to be default.
Alternative method provided by Frank Lion, edited by Ed.
For normal builds, I use the same method as Ed (not that surprising since I learnt it from Ed, haha) but for beta builds, which I trust about as far as I can throw them, I use the following method, in the interest of high speed and Mozilla folder security:
1. Download a ZIP build of beta. (nothing gets installed when using zip builds )
viewtopic.php?t=613368 = 12-19-07 Minefield Nightly thread in Builds
Follow the 'NEW All Linux, Mac and Windows hourly builds for the last 14 days NEW' link.
2. Go to your existing 'Mozilla' folder (it will be Doc&Settings/Whatever/Apps Data/Mozilla) make a backup copy of it and paste it somewhere. Then rename the one in Apps Data to 'MozillaMAIN'.
3. Make a folder in your C Drive or whatever and call it 'Firefox 3'. Put your zip into it, and unzip it into that folder.
4. Go into the unzipped folders and find 'firefox.exe' and double click it - it will make a NEW Mozilla folder and you are away.
5. When you are finished fiddling, delete this new Mozilla folder (or rename it Mozilla-B3, if you want it again), rename your 'MozillaMAIN' back to 'Mozilla' and fire up your Firefox 2 again.
6. Do not use your beta zip build again, without repeating the above steps again! Possible 'world of pain' type stuff otherwise.
See? very quick and totally risk free, I do it like this all the time with betas.
Notes: It is not advisable to have either version of Firefox set as the default browser - use K Meleon or even IE for this, otherwise some obscure program that you forgot you had, will one day, open up it's 'Help' page using the wrong version of Firefox and wreck the other version profile.
Additional information from urichter edited by Ed.
The Command Line Option -profile option is also noteworthy: Just use firefox -profile c:\some\path\to\profile in the Start > Run box, and firefox will use this folder as profile folder. The folder just has to exist, if its empty, a new profile will be created there.
The second advantage: The profile doesn't have to be registered in the Profile Manager or the profiles.ini file. No risk to mess up the default profile if you just want to start a different version!
Ed
Also edited to replace -p with -P steviex
01-07-08 edit:
-p works for some users, while others might need to use -P, while others yet may need to use -ProfileManager or -Profilemanager - use whatever works on your system, if one doesn't works try another.
I am seeing no difference in recent Minefield builds on either W2K or WinXP with using -p as reported by a few users, either -p or -P works just as good for me as it has for a long time.
Ed
Miscellaneous edits to reflect version changes, and additional info added... steviex
