How to Fix: Firefox Links Suddenly Open in New Window, Profile

Dennis Faas's picture

Infopackets Reader Sammy G. writes:

" Dear Dennis,

I have a very strange problem. A few days ago my system upgraded to Firefox 67. Now every time I click on an external link, a new Firefox window opens up instead of the link opening up in my existing Firefox window. Also, the new Firefox window doesn't have any of my addons enabled, which is strange. Before Firefox upgraded, all links opened up in my existing Firefox window. I have tried fixing the problem by setting Firefox as my default browser. I have also tried resetting my Windows 10 Default Programs browser to Edge, then back to Firefox, but that didn't work. I have also tried modifying the default file association for .htm and .html files; I have also adjusted the default protocol for http and https to Firefox and Edge and back again. I don't understand why my external links are opening in a new Firefox window instead of the one that's already open and running. Can you please help? This is driving me crazy! "

My response:

I asked Sammy if I could connect to her machine using my remote desktop support service in order to have a closer look, and she agreed.

Below I will discuss my findings.

How to Fix: Firefox Links Suddenly Open in New Window, Profile

After much research, it appeared that all external links were running on a new Firefox profile.

This would explain why Sammy's addons weren't enabled whenever the "new" Firefox window opened up when an external link was clicked. I can't say for sure, but it appears that the new Firefox 67 upgrade created a new profile called 9z6vdn7g.default-release (on Sammy's computer, at least); from then on, any external link pointed to the new Firefox profile instead of the previous one.

To fix the problem, I deleted the newly created Firefox profile, then set her old profile as the default.

To do so:

  1. If you are using the standard Windows 10 start menu, click Start, then type in "run" (no quotes), then press Enter. The "Run" box will appear; inside that, type in "firefox -p" (no quotes), and press Enter. If you are using Classic Shell, simply type in "firefox -p" (no quotes) and press Enter.
  2. The "Firefox - Choose User Profile" window will appear. From here, you will need to figure out which of the profiles listed is the newly created one (when Firefox updated last), then delete it using the Profile Manager. It may help to look at your C:\Users\[Your User Name]\AppData\Roaming\Mozilla\Firefox\Profiles directory to compare byte sizes. Note that if you delete the wrong profile, you will lose all your previous settings and addons, etc. If you are not sure, you can contact me for remote support and I will do it for you.
  3. Now that the erroneous profile is deleted, highlight your old profile and then check mark the "Use the selected profile without asking at startup" option. Next, click the "Start Firefox" button. Firefox will launch.
  4. Wait a few seconds, then close Firefox. Next, click an external link (in an email program, for example). On Sammy's computer, the Firefox profile manager launched again, though this was not expected behavior. I ensured that everything in the profile manager was selected again as mentioned in Step #3, then clicked "Start Firefox". I then tested external links and they now opened in the same Firefox window. I then closed Firefox again, opened it up (again), then tested external links and all was working as it previously was.

Problem solved. I hope this helps anyone having the same issue.

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About the author: Dennis Faas is the owner and operator of With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.

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