Sharing Firefox and Thunderbird profiles across a dual-boot

18 Jan

I’m currently trying to see if WinXP x64 will meet all of my hardware and software compatability needs so that I can fully utilize the 4GB of RAM I got for Christmas, so I am dual-booting between XP x32 and x64, with each install on a different drive. I set up Firefox and Thunderbird, but wanted access to my settings and more importantly, my saved passwords that I have configured on the x32 install.

I could have just copied the profiles over, but the profiles won’t stay in sync without a considerable amount of effort, if I am constantly switching back and forth. What if I bookmark something in x64? When I run FireFox on x32, I want that to show up in my bookmarks. Same goes for my extensions and any other settings. Turns out, it’s not very difficult to do, but it does take a little bit of work:

First boot into the newer of the two installs. In my case that’s XP x64.

Get ntfslink, a handy shell extension that lets you create and manage hard links and junction points through explorer. What we care about is the ability to create a junction point, which you can read about if you are truly interested. The general idea is that a junction point acts like a sort of shortcut, but it makes it look like the thing your shortcut is pointing to is actually there.

Find your original profile. Something like c:\Documents and Settings\username\Application Data\Mozilla\Firefox\profiles\somestring.default
Your new firefox appdata should be pretty similar. In my case it’s exactly the same except with the drive letter d: instead of c:, because that’s where I installed x64.

In d:\Documents and Settings\username\Application Data\Mozilla\Firefox\profiles\ (or wherever your newer OS install lives) create a NTFS junction point to c:\Documents and Settings\username\Application Data\Mozilla\Firefox\profiles\somestring.default (or wherever your older OS install lives) by navigating to the new profile directory, right-clicking in a blank space, and choosing New | NTFS Junction Point. Ntfslink names your junction “link to somestring.default” by default. Rename that to just somestring.default for simplicity.

For completeness, you should do the same thing between d:\Documents and Settings\username\Local Settings\Application Data\Mozilla\Firefox\profiles\ and c:\Documents and Settings\username\Local Settings\Application Data\Mozilla\Firefox\profiles\somestring.default

In d:\Documents and Settings\username\Application Data\Mozilla\Firefox\profiles\profiles.ini you should see something like this:

Copy that and paste it at the end of the file. Change Profile0 to Profile1 (assuming you only had one profile previously). Change Name=default to something more useful. In my case I went with Name=jay Change Path=Profiles/… to Path=Profiles/somestring.default

Save profiles.ini, and then start firefox from the run menu with firefox -p — this should prompt you for which profile you would like to use. Choose the name that matches what you set in the previous step, in my case “jay.”

If you followed these steps carefully then you should now have the same set of extensions, preferences and bookmarks that was on your old install, and changes made on one OS should carry across to the other.

The steps I spelled out here for Firefox profiles are identical for Thunderbird profiles, just substitute Thunderbird wherever you see the word Firefox.


Leave a Reply


  1. olo

    June 1, 2009 at 5:04 am

    its no need to use junctions. just point to your profile in profiles.ini, turning “relative” to 0, something like this

    Path=D:\Documents and Settings\olo\Dane aplikacji\Mozilla\Firefox\Profiles\78ny8sbd.default

    i’m using this with success on xp/win7 dual boot.

  2. Jay

    June 1, 2009 at 2:59 pm

    Good point. I must confess that I have an irrational love for creating junction points, I probably tend to use them even when there are simpler solutions, but they seem so elegant to me.

  3. cyclotis04

    July 8, 2009 at 12:27 pm

    Could you use this method to share profiles between a dual boot Windows/Linux system? Or would differences in the file system prevent that?

    What about using Dropbox and junctions to sync profiles across the web?

    Great tutorial, tho. Thanks — I was looking for something like this!

  4. Jay

    July 8, 2009 at 4:06 pm

    Good questions! I don’t think the junction/sym links will work across different file systems, but olo’s suggestion above should work fine with that (as long as your profiles are stored in a FS both operating systems can read/write).

    Not sure about Dropbox, as I’ve never used it, but if you try it out please do let us know how it works for you…might give me a rason to try Dropbox!

  5. bruce

    January 31, 2010 at 3:51 am

    I’ve been trying without success to get Thunderbird to use the same profile for mail on a Win XP 32 bit/Windows 7 64 bit dual boot. XP is my primary OS. My Thunderbird profile is located on a separate drive, Drive E:. I tried changing the profiles.ini like olo suggests and have tried using Mozbackup. I’ve got the Win 7 install to enumerate the number of emails, but it gets stuck “determining what messages to index” and when I turn that off that message goes away, but I still can’t view my email. I’m going crazy!

  6. Jay

    January 31, 2010 at 9:18 pm

    I’ve discovered an easier way since writing this article, I guess I should have updated! I’m not sure if it will resolve your specific issues, but it’s worth a shot.

    Start up thunderbird.exe with the /p option. It will come up and ask you to choose a profile. If you choose “Create Profile” it will ask you for a name. Pick something that you’ll be able to recognize as your “shared” profile later, and select “Choose Folder…” and locate your existing profile.

    Although all of this implies that you’re choosing where it is going to create a brand new profile, what actually happens is that it sees your existing profile and uses that one instead. I’ve used it successfully on two different machines now, and it has always worked perfectly. There may be something that olo’s trick misses that thunderbird /p gets right.

  7. bruce

    February 21, 2010 at 5:47 pm

    Well, the way I ended up making this work was to reduce the number of messages in my inbox. I had a lot. I spent a night filing them into subfolders and deleting those I didn’t want. I then make a backup with Mozbackup. I copied my profiles folder. Then I restored the backup with Mozbackup. All my messages were there and readable except the few in the inbox. I copied the inbox files from the profile copy I made and that was it. It now works from both XP and Win7.

    Thanks for all the help and suggestions.

  8. Matthew C. Kriner

    March 7, 2010 at 5:32 pm

    Blogs RSS feed doesn’t work in my browser (google chrome) how can I fix it?

  9. nomis

    August 19, 2015 at 1:38 pm

    I do wish [email protected] would follow this and make an addon… The linux revision could be set to find the windows installation automatically, etc….