Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

While browsing Firefox, display another htm*file by double-clicking it in Windows Explorer and not getting the erro message "Firefox is already running (etc) "

  • 8 replies
  • 1 has this problem
  • 1 view
  • Last reply by cor-el

more options

While browsing the Web with Firefox, I often want to view an htm (or html etc) file that is recorded on my computer, by double-clicking it in my Windows Explorer, hoping it will open automatically a new tab. When I try this now, I get the error message "Firefox is already running (etc)" . In my current setup, Firefox is associated with the htm and html file name extensions. If, instead of double-clicking the filename in the Explorer, I choose the Firefox menu item "Open a file", this works OK. In old versions of Firefox, double-clicking a filename in the Windows Explorer or File Manager caused Firefox to open a new window every time which was ok. I have the same problem with Thunderbird, which I have associated with the "eml" file name extension. How can I view a series of recorded ".eml" files with Thunderbird when Thunderbird is already running ? Thank you.

While browsing the Web with Firefox, I often want to view an htm (or html etc) file that is recorded on my computer, by double-clicking it in my Windows Explorer, hoping it will open automatically a new tab. When I try this now, I get the error message "Firefox is already running (etc)" . In my current setup, Firefox is associated with the htm and html file name extensions. If, instead of double-clicking the filename in the Explorer, I choose the Firefox menu item "Open a file", this works OK. In old versions of Firefox, double-clicking a filename in the Windows Explorer or File Manager caused Firefox to open a new window every time which was ok. I have the same problem with Thunderbird, which I have associated with the "eml" file name extension. How can I view a series of recorded ".eml" files with Thunderbird when Thunderbird is already running ? Thank you.

Chosen solution

You need to remove that environment variable. It shouldn't be there at all. If it is needed to run multiple Firefox instances at once then add the -no-remote switch to a desktop shortcut.

See also:

Read this answer in context 👍 1

All Replies (8)

more options
more options

I forgot to mention that Firefox is already my default Web browser : clicking a Web link like "http://........etc (when Firefox is not already running !) " will cause Firefox to open and display the web page fine!. But, when Firefox is already running, if I click a Web link in another application, say Thunderbird, it will not open a new tab in Firefox for it, as expected, but it will open an error window saying approximately: "Firefox is already running but does not answer. To open a new window, you must first stop the Firefox process or restart your system." The only way to have Firefox opening up the web link without first closing it, is to copy the link to the clipboard and then pasting it into the Firefox address area. A bit disappointing....

more options
more options

Check the target field in the Firefox desktop shortcut and make sure that you do not start Firefox with the -no-remote switch or have set the environment variable MOZ_NO_REMOTE=1 (Control Panel > System > Advanced > Environment variables).

more options

The target field of the desktop shortcut is "D:\C_Mozilla Firefox\firefox.exe" (no switch)

The system/environment variable MOZ_nO_REMOTE is now 0, changed from 1, but I can see no difference. Maybe I need to restart the system to get a change ? Thank you.

more options

Chosen Solution

You need to remove that environment variable. It shouldn't be there at all. If it is needed to run multiple Firefox instances at once then add the -no-remote switch to a desktop shortcut.

See also:

more options

I removed the only mention of MOZ_NO_REMOTE from the system environment variables and, see there, it is all OK now. Not even need to create a profile. And it also works the same in Thunderbird. I shall see in the coming days if any refinement is needed (profiles etc), but it does not look like that. Problem solved. Thank you very much Marylin

more options

You're welcome.