If you have Windows 10 or 11, and Webroot security software, and 64-bit Firefox 97, there is an incompatibility which cripples Firefox.

People are working with Webroot to issue an update.

If you do not run Webroot security software, please ignore the rest of this.

Until then, a user posted that one workaround is to run Firefox 97 in backwards compatibility mode. I haven't tested this myself, but here is how you would set that up:

(1) Open the Properties dialog for your Firefox shortcut. Either:

• right-click a Desktop shortcut, then click Properties
• right-click a pinned Taskbar icon, then right-click the Firefox (or Mozilla Firefox) item, then click Properties

(2) Switch to the Compatibility tab

(3) Check the box for "Run this program in compatibility mode for"

(4) If the selector for that option is not set on Windows 8, switch it to Windows 8

(5) Click OK and then start Firefox (if Firefox won't start because it is already running, you might need to restart Windows)

As a result of this change, you may notice that some Windows 10-specific features and styling are disabled. However, I am not aware of any major changes. If you experiment with this, let us know your experience.

Yes I have webroot.

Another user reported that uninstalling and reinstalling WebRoot solved their problem, but it might have been the business version, so I'm not sure that applies to all WebRoot users.

I went to webroot forum and someone suggested others to try this and it work for me. I fixed this by opening Webroot, going to Identity Protection => Application Protection. Firefox was listed. First thing to try is click on the Allow radio button. Close webroot then see if firefox works.

If not then go back into Webroot Identity Protection => Application Protection and right click on the firefox entry and delete it. Then click Add protection at the bottom and navigate to firefox.exe and add this. Finally click the Allow radio button

Replied too quickly. My extensions in firefox became unable to use in the previous solution. So I just tried the uninstalling and reinstalling webroot and now firefox works and the extensions.