Am running Windows 11 24H2 with CoffeeCup HTML Editor version 18 build 890.

I want to add Firefox as an Additional Browser. Went to Tools | Additional Browsers | Edit Additional Browsers.
That opens the Preferences dialog to the Browser Testing tab. In the Select a Browser field, using the file manager button navigate to:

\Users[i]acct[/i]\AppData\Local\Microsoft\WindowsApps\firefox.exe.

Pressing enter display the dialog box shown the the attachment.
What am I doing wrong, please. Thanks.

On my PC (win. 11) the path to Firefox is C:\Program Files\Mozilla\Firefox\firefox.exe

Try that.

Thank you. After uninstalling my Firefox, then re-downloading the Firefox installer and running it, Firefox.exe was placed as you cited. Coffeecup liked this location. All is well.