The Profile Manager still exists in Firefox 4. Just use the -ProfileManager switch.

Please note that the removal of the Profile Manager is being discussed for Firefox 5.

I need more help that what you've provided. The profile manager pops up, however, it logs me into the same profile each time I choose one, regardless which one I choose. If I'm logged into one profile, when I click on the next one to use, it automatically logs me into the currently running one. How can I stop this? All was pretty good before the upgrade, now it stinks. I've uninstalled FF4 and installed FF 3.6.15 as suggested but the profiles are still messed up. HELP!!!!! Please

FF 3.6, Win 7: Two separate profiles stored in different directories. I had each profile pinned to the taskbar and could launch each separately using the -no-remote option: "C:\Program Files\Mozilla\Firefox\firefox.exe" -p MyFirefox -no-remote "C:\Program Files\Mozilla\Firefox\firefox.exe" -p default -no-remote After the upgrade to FF4 selecting either launcher initiates the same session. it is possible to run the profile manager: "C:\Program Files\Mozilla\Firefox\firefox.exe" -profilemanager When this appears, two profiles are listed in the window, a mouse-over hover shows where the profiles are located: MyFirefox: C:\Users\james\AppData\Roaming\Mozilla\Firefox\Profiles default: C:\Users\james\AppData\Roaming\Mozilla\Firefox\Profiles\rpwsq3sr.default Solution(ish): I created a new profile using profile manager. Copying the contents of the 'MyFirefox' profile over the newly created profile in the Profiles directory (excluding the rpwsq3sr.default directory of course), so there's now two profile sub-directories. This does allow me to run different concurrent firefox sessions, however the taskbar pinned shortcuts no longer represent the running instance: all running instances are linked to the 'default' firefox pinned taskbar icon. Which really defeats the whole objective!

You can't use the -no-remote switch through the Profile Manager dialog window, and that is what is needed to launch additional simultaneous Profiles. That switch has to be run from command line or the Target line in a desktop / taskbar shortcut.

The Profile Manager dates to Firefox 0.9, where the -no-remote switch didn't come about until Firefox 2.0 versions, and the Profile Manager wasn't modified to take advantage of it. IIRC, that is right about the time that the Mozilla developers started talking about doing away with "Profiles" altogether, which will probably happen in Firefox 6.0 or 7.0 later this year.

This is a REAL BIG DISAPPOINTMENT!!! There is a huge percentage of users who are currently using Firefox's profile management. Most of these people I would assume are involved in some type of business. They use profile management (particularly with the -n0-remote switch) to separate work, play, research, their home business, etc. So what will happen to these people and their profiles? I really hope that the FF dev team has something better up their sleeves. I cannot figure out why they would get rid of this! Its not broken so why fix it! There are 4 reasons why I stay with Firefox 1. Bookmarks management, 2. TabGroups extension, 3. BarTab extension which can be replace by setting browser.sessionstore.max_concurrent_tabs to zero (0) [which by the way should really be made an option somewhere in the Firefox menu], 4. Simultaneous profile management using the -no-remote switch. Why get rid of one of your biggest advantages during this browser war between Firefox, Chrome, IE9, Opera and Safari? Just does not make any sense at all to me. If there is anyone (especially from the FF Dev Team) who wouldn't mind explaining the reason behind this, I would greatly appreciate it, thank you.

There is a new utility available for those who use multiple profiles. I have been using it to launch Firefox since I discovered it for the multiple Firefox versions and profiles on my system. See: https://developer.mozilla.org/en/Profile_Manager

After months of trying to get my separate profiles to show up separately on the taskbar (win7), which it did wonderfully in 3.6, I have finally had to switch to Chrome.

It's not a perfect solution. I miss my Firefox, and will use it where needed, but the time I am taking trying to get Firefox to do what it used to (simple profile management) is too much. I'd rather use that time to figure out how to do it in Chrome.  :(

I still prefer FF, and hopefully will switch back. But usually when one makes the switch to another browser, they don't look back.

If this is all temporary glitches, then say so. I'm hoping this fad of fast-pace development tied to a calendar release date ends soon.