How are you opening Firefox ... from an icon on the desktop or in the dock?

What happens when you open Firefox from the Applications folder?

I think you downloaded the firefox and installed it ..

Instead of "Replace" you clicked "keep both" , so the issue arrises.

First Quit the Firefox and Eject the Firefox Application.

Goto Launchpad and Open the Firefox

See this previous question and the remedy posted by shahriar5252:

/questions/755642 The window asking me to drag Firefox to the Applications folder loads every time I open Firefox.

Another user suggested: 1. Delete Firefox from dock 2. Access Firefox from the applications folder 3. Save it to the dock This solved the problem. Firefox is now working normally. Thanks.

More info, in case it helps anyone else with this problem:

I got a PM from waycool007 on 10/12/13 which said,

Hi Alice -

Thanks for trying to help me - regarding the question regarding the firefox dialog box.

I am opening firefox from the icon on my dock. It then opens the annoying installation/dialog box.

If I open firefox from the applications folder, it actually opens properly. 

... to which I answered,

You need to close Firefox if open and then delete the Firefox icon that is in the dock. You can then start Firefox from the applications folder and, when the new Firefox icon shows up in the dock, use the control click option to keep it there.

Let me know if this fixes it. 

I just got this reply:

I followed your instructions, and Firefox is now working normally. This has been bugging me for at least two months, and you solved it in a minute. Wow. Thanks! 

(You're welcome!)