When I run

firefox --new-window <url> &

Firefox starts. When I run it again, I get an error dialog reading:

Firefox is already running, but is not responding. To use Firefox, you must first close the existing Firefox process, restart your device, or use a different profile.

The expected behavior is that a second window opens on the same web page.

How do I fix this?

Note that I do not want instructions on how to kill the existing Firefox, or to remove lock files. Everything else about it is working fine. It just isn't taking the remote command.

  • Do you use multiple profiles with firefox ? Maybe you have multiple instances of firefox running ? Maybe the problem is related with the OS ?
    – Marco
    Commented Jul 26, 2023 at 15:32
  • @Marco After the first failure, I deleted all profiles and made a new one. No help. Made a second profile, no help. OS issues? maybe, but what should I try?
    – David G.
    Commented Jul 26, 2023 at 16:06
  • Unfortunately I don't know how firefox handles this and it works on my system. Ask somebody of the firefox developer or try debugging it: firefox-source-docs.mozilla.org
    – Marco
    Commented Jul 27, 2023 at 11:55

1 Answer 1


It turns out that they replaced the classic X-based ICCCM-conformant open URL command with something dbus based.

So if you remove dbus, you get this error.


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