One thing I forgot to mention: The Profile Manager ("Firefox - Choose User Profile") window does open on the 2nd desktop. Only after I select the 2nd profile and click the Start Firefox button (still on the 2nd desktop), the Profile Manager window disappears and the Firefox window (with the selected profile) opens on the 1st desktop. I don't know enough about the Firefox source code but since it used to work with older Firefox versions, I am suspecting somewhere in the code for opening the main Firefox window (but not for the Profile Manager window) there is a piece of code which forces the window to the 1st desktop.

You can check for problems with the localstore.rdf file and try to delete the localstore.rdf in that second profile.

• http://kb.mozillazine.org/Corrupt_localstore.rdf

Thanks for the info, but it didn't make any difference. Also, I would be surprised if the desktop index for Firefox' main window was saved as part of the localstore.rdf file. Something else must have changed in one of the more recent versions of Firefox, forcing the main window to the first desktop. But why?

This was broken in version 12 , and it doesn't show up in the list of "known issues" in the newer versions. Does this imply that there's no plan to fix it ? Am I stuck with version 11 as long as I want to use Desktops ??

Thanks Tom93, for pointing me to the other support thread. I'm glad I'm not the only one with that problem!

Just tested with the current 16.0.2 version, the problem is still there. In the meanwhile, I found another question related to this problem:

"Firefox does not open in more than one virtual desktop of sysinternals' Desktops utility" https://support.mozilla.org/en-US/questions/814434?esab=a&as=aaq

Interestingly, all of the other threads are closed, so no new answers are accepted - even though no solution has been found.

The link I mentioned has an answer pointing to a blog site, which explains how to set up multiple profiles in order to start Firefox on the second desktop: http://blog.dpjonline.com/tag/sysinternals-desktops/

As I pointed out in my original post of this question, I was already doing this so this is no solution either.

How does this site here work in general? What is the outcome of these questions? In my opinion, this particular question should be turned straight into a bug report so some developer will work on fixing this issue.

Alright, finally I have some news on this issue which might actually be helpful!

After I had created a new thread in the mozillaZine Forum titled Firefox does not start on second desktop, I received an answer which suggested to try and use a direct Firefox profile shortcut instead of starting the Profile Manager. That way, you need to create three more Firefox shortcuts using the -p option (i.e. -p "Desktop 2" if your FF profile for the second desktop is called Desktop 2) if you want to use Firefox on all 4 desktops.

So for me, the targets for the four Firefox shortcuts (one for each desktop) look like this:

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -p "default"

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -no-remote -p "Desktop 2"

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -no-remote -p "Desktop 3"

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -no-remote -p "Desktop 4"

Hope that helps someone out there!

Since I still believe that it is a Firefox bug (a user is no able to use the Profile Manager on a desktop other than the default one), I created a bug report:

https://bugzilla.mozilla.org/show_bug.cgi?id=808891

If you are affected by this problem as well, please comment on that bug so it will get some attention from the developers.

If you are looking to have the Mozilla developers do any fixes to the Profile Manager system in Firefox, you're "beating a dead horse". BSmedberg has been commenting in Profile related Bug reports for well over 7 years that the Profile Manager will disappear "someday" - they aren't going to fix it. The Profile Manager XUL Runner application is the replacement for the built-in Profile Manager.

IMO, you are better off just using the command line launch to Profiles for the 2nd and subsequent "Desktops", as you have posted about having done already.

Thanks for that info, Edmeister.

Quite interesting what discussions the Profile Manager caused at the link you posted and its continuation on Google Groups: https://groups.google.com/forum/?hl=en&fromgroups=#!topic/mozilla.dev.planning/BpALi5fCZV0

Out of curiosity, I downloaded the new Profile Manager version 1.0 and tried it on multiple desktops. Although it complains about the profiles I want to start being locked even with no Firefox instances running, it (after a confirmation) let me run them anyway and Firefox started even on desktops different from the default one.

I am not really happy about the size (16Mbyte download, 35Mbyte installation, 50Mbyte RAM consumption after start) for a simple application to manage and start profiles - I think that could be done in ~1Mbyte, (Desktops.exe is about one tenth of that size) but I guess that's what a full-blown XULRunner-based application will always look like.

Therefore, I am probably going to stick with the shortcuts I created for the different Firefox profiles on different desktops. For everyone who really needs a Profile Manager and wants to use it to start Firefox on multiple desktops, the new Profile Manager does get the job done.