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Getting "Firefox is already running..." when trying to open a local htm file.

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  • Last reply by cor-el

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I have multiple Firefox profiles and I start Firefox with the -no-remote command line option. If I don't have any instances of Firefox running, I can open any local .htm/.html file (it will open with the default Firefox profile) but if an instance of Firefox is already running and I try to open a local .htm file (or if for example apps like JDownloader are trying to open a web page with the default browser which happens to be Firefox on my Win10 machine) I get the following error:

Firefox is already running, but is not responding. Te old Firefox process must be closed to open a new window.

Are there any tricks to fix this (Firefox command line options or Windows registry "hacks")?

Thanks in advance for your responses!

I have multiple Firefox profiles and I start Firefox with the -no-remote command line option. If I don't have any instances of Firefox running, I can open any local .htm/.html file (it will open with the default Firefox profile) but if an instance of Firefox is already running and I try to open a local .htm file (or if for example apps like JDownloader are trying to open a web page with the default browser which happens to be Firefox on my Win10 machine) I get the following error: Firefox is already running, but is not responding. Te old Firefox process must be closed to open a new window. Are there any tricks to fix this (Firefox command line options or Windows registry "hacks")? Thanks in advance for your responses!

Modified by AltairAC

Chosen solution

Note that you can't open links in a Firefox instance that is started via -no-remote. You can drag the file in a Firefox tab or to the new tab plus button or don't use the -no-remote command line switch for you default profile, use it only to open additional profiles.

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I don't know if this will help. This is the batch file I use; (one line) C:\PROGRA~1\MOZILL~1\firefox.exe -no-remote -new-instance -new-window -P Firefox_v_57

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This is a confusing area. I have two versions of Firefox set up to run in two separate profiles:

Firefox 57 => Quantum profile (run using -no-remote)

Firefox 52 ESR => Legacy profile (run using -no-remote)

Firefox 57 is my primary browser and is usually already open when I click a link in another application.

Over the years, I've created many profiles for testing various add-ons, and my current default profile is one of those test profiles. When I click a link, or launch a local file, it opens as a new tab in my Firefox 57 session. I think this works because Firefox isn't try to open a new Firefox session in a profile I'm already using. Instead, it detects that Firefox is already running and simply re-uses it.


If you want to try that by setting a different default profile:

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

If you already have an extra profile: scroll down to it and click the Set as default profile button below that profile. You're done.

If you do not have an extra profile: click the Create a New Profile button, then click Next. Assign a name like Dec2017, ignore the option to relocate the profile folder, and click the Finish button. After creating the profile, scroll down to it and click the Set as default profile button below that profile. You're done.

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Chosen Solution

Note that you can't open links in a Firefox instance that is started via -no-remote. You can drag the file in a Firefox tab or to the new tab plus button or don't use the -no-remote command line switch for you default profile, use it only to open additional profiles.