Operating System: Windows 11, Version 25H2

Kaspersky Application: Kaspersky Password Manager (Version 25.1.0.602)

Problem Summary: I can't install the Password Manager extension on Firefox. In 'Browsers' (in 'Settings' on the Password Manager app), Firefox isn't listed as an option, only Microsoft Edge. (See image below.)

Extra Details: I recently purchased a new laptop. I installed Kaspersky and Firefox, but the option to install the Password Manager extension doesn't appear for Firefox (I've managed to install the Kaspersky Protection extension without issue). I have, however, been able to install the Password Manager extension for Microsoft Edge. I've tried uninstalling Kaspersky and Firefox, but the problem persists. I haven't had this issue on any of my other devices. As far as I'm aware, there isn't any other way to install the extension.

Edited December 10, 2025Dec 10 by Michael A
Making the text clearer.

What version of Firefox do you have installed?

The version is Windows MSIX package (mozilla-MSIX - 1.0), 146.0 (64-bit).

I think that's the problem.

Try installing the regular version (not MSIX) from https://www.firefox.com/ 

Thank you. The Firefox browser option appeared in the Password Manager app after I reinstalled Firefox using the link you provided, and the extension is now installed and working. For reference, I believe the issue was that I installed Firefox from the Microsoft Store.