ljv777, does it work if you remove the URL address (plus the space that preceeds it) from the end? Or try a different URL?

Or does it work from the Windows run dialogue box (win+R)? For example, if you enter: "C:\Program Files\Mozilla Firefox\firefox.exe" -new-window https://wiki.mozilla.org/Firefox/CommandLineOptions

(you may need to adjust the Firefox install path if yours is different)

If this works as a run command, then you should make sure that the taskbar icon's target field contains the exact same path.

If nothing here works and no-one else suggests anything else, then you might try creating a taskbar icon that points to: cmd /c "C:\Program Files\Mozilla Firefox\firefox.exe"

(again, adjusting the Firefox executable's path if necessary)

Hello and thanks for an informative reply. Running via Win+R with the address you suggested ("C:\Program Files\Mozilla Firefox\firefox.exe" -new-window) worked, but it still didn't work when I typed the same address into the Firefox target box and adjusted the second line so that it was the same there ("C:\Program Files\Mozilla Firefox"). When I tried your last suggestion "cmd /c "C:\Program Files\Mozilla Firefox\firefox.exe") I got "invalid address". Do you have any more suggestions? (I'm not that used to tinkering with computers , so I appreciate your patience.)

ljv777, in the first post you said that adding the "-new-window URL" command line to the taskbar icon doesn't work. What happens exactly? Does Firefox show a pre-existing window? Or does nothing happen at all?

If a pre-existing window is shown, then is it possible that a new window might have been launched in the background? Have you tried glancing through the alt+tab menu or hovering the mouse pointer over the Firefox taskbar icon, to see if a new window has opened in the background?

In the latest post you say that you typed the text into the target field. Did you literally type it or did you copy and paste? If you typed, then you might want to try copy and pasting to rule out typos?

When you say that you got an "invalid address" error, is "C:\Program Files\Mozilla Firefox\firefox.exe" the correct install path for your system?

If it is, then was this error after trying the cmd suggestion in the Run command box, or after editing the Firefox taskbar icon? If you did the latter, then perhaps the Start in field needs to be adjusted also. But maybe it would be best to start with a new icon for the cmd command, see #3 below.

Here are some other things that you could try.

1. Try unpinning Firefox from the taskbar, restarting the computer, repinning a normal Firefox shortcut then edit its taarget to append "-new-window" or "-new-window URL" (without the quotes of course, and remembering to include a space before the added text). You might also wish to restart again before testing.

2. Try pinning Firefox from alternative sources. Such as from a shortcut on the desktop or one found in Windows Start, or launch Firefox then right-click its running icon and pin from there. You could try editing the target fields of the icons pinned from these various sources and see if one works.

Or, as a last resort: 3. Right-click on the desktop and select New > Shortcut. In the wizard that opens, enter the location: cmd /c "C:\Program Files\Mozilla Firefox\firefox.exe" then follow the rest of the steps. Once this shortcut has been created, try pinning it and test. If this works, then you can edit this shortcut to change its icon to the normal Firefox icon as found in Firefox.exe. You could also try the following locations instead: cmd /c "C:\Program Files\Mozilla Firefox\firefox.exe" -new-window cmd /c ("C:\Program Files\Mozilla Firefox\firefox.exe" -new-window)

Thanks again for your very informative answer.

As I said, I'm not good with computers, but from what I've been able to discover, the path is not correct. It seems to be two Mozilla Firefox on my computer, one under Programs and another under Users. The path I get when I right-click on the Firefox icon shortcut is the one in Users, but then the very last file in the target bar doesn't match – “firefox.exe”. There is no such file in my explorer (I can't find it when I use the search function). So I guess that's where the problem is.

If I don't write firefox.exe at the end, what do I write, do you think?

ljv777, typically Firefox is installed to either "C:\Program Files" or "C:\Program Files (x86)", whereas your profile data such as bookmarks, history etc are stored under "C:\Users".

You need to have the Firefox executable file pinned to your taskbar. Once you have the correct .exe file pinned, you should be able to add command line arguments to it as normal.

I suggest that you try the following:

1. launch Firefox and make sure that all your bookmarks etc. ar present
2. unpin any pre-existing Firefox icons from the taskbar
3. right-click the running Firefox icon on the taskbar and pin it from there
4. close all Firefox windows
5. restart your computer
6. edit the newly created taskbar icon to add "-new-window URL" or "-new-window" at the end of the target field (remembering the space inbetween the original path and the added argument, and to not include quotes around the added argument)
7. restart your computer

Hello again and thank you very much for taking the time to try to resolve this issue. Strangely enough it doesn't work, yet, but there is a person that I can consult and then I will show him your various advices. Surely he will be able to help me to do as you suggested in the right way. Many thanks, once again!