Firefox is opening twice instead of once, usually the "wrong" one opens

A few questions:

What operating system are you on?

Can you describe how Firefox is being launched? Is this happening when you open it from the taskbar/dock, start menu/spotlight search, or something else? Or happening when you boot your computer perhaps?

When you say "the version with the preset tabs" and "the version you don't want"... are you talking about actual Firefox version numbers (like 157 or 158)? If not, what is the difference between them that makes you know "this is the right version and this is the wrong one"?

I use Windows 11. The Firefox window I want is v 159.0. It opens to the NY Times automatically on startup. The Firefox window I don't want ) is v 158.0.1. It opens to Firefox automatically on startup. I want to get rid of the latter. I do not need 2 different Firefox windows open. It just slows everything down.

Thank you for suggestions to help me get rid of the v 158.0.1 window.

There are two main ways to start Firefox:

(1) Using a Firefox icon

If you check the Help > More Troubleshooting Information page after doing this, is it the correct version? On that page, take note of the "Application Binary" location. Normally, it's

C:\Program Files\Mozilla Firefox\firefox.exe

or sometimes

C:\Program Files (x86)\Mozilla Firefox\firefox.exe

(2) Launching a document or link from outside Firefox and letting Windows send it to Firefox

If you do this, does Windows fire up a different installation of Firefox? One important clue would be whether it lists a different "Application Binary" location.

Based on which one is the "correct" Firefox, the fix will vary. Let us know what you find.

Sorry, I missed the part about starting automatically when you boot windows.

In the Firefox you do not want to start automatically, could you check:

(1) Settings page

In the left column, switch to "Home and startup"

If there is a check in the box for "Open Firefox automatically when your computer starts up" uncheck that

(2) Quitting

When exiting this version of Firefox, use the menu to make sure no hidden windows are still running. Either:

• menu button > Exit
• File menu (Alt+F) > Exit

One tool to investigate programs that run at system startup is Autoruns from Microsoft/SysInternals. For more information, see: https://learn.microsoft.com/en-us/sysinternals/downloads/autoruns

Yes, I had my settings configured so Firefox would start automatically. I changed the setting and now open Firefox from an icon on the task bar. That seems to solve the problem! Thanks

Sounds good for now. If you do notice the other one opening unexpectedly, or you decide to remove it for security hygiene reasons (to not have old versions with vulnerabilities sitting around), try the steps in my earlier reply.