We've never seen this popup. Can you provide any details about this issue?

"Before you continue" is from the website. Not Firefox.

For attention of TyDraniu. The pop up is from Google and pops up every time I do a fresh search. I have added a screenshot of the popup

This is a question to Google Support, we don't know "why" you see this popup. Perhaps they want you to sign in.

Thanks, I was beginning to think that, but why it has just started and only on Firefox for windows is another matter

Perhaps something is wrong with the Google cookies. Many site issues can be caused by corrupt cookies or cache&#46; '''Warning ! ! ''' This will log you out of sites you're logged in to&#46; You may also lose any settings for that website&#46; * [https://support&#46;mozilla&#46;org/en-US/kb/delete-cookies-remove-info-websites-stored Delete cookies to remove the information websites have stored on your computer] {web link} * [https://support&#46;mozilla&#46;org/en-US/kb/how-clear-firefox-cache How to clear the Firefox cache] {web link} If there is still a problem, '''[https://support&#46;mozilla&#46;org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode]''' {web link} by holding down the '''<Shift> ''(Mac=Options)''''' key, and then starting Firefox&#46; A small dialog should appear&#46; Click '''Start In Safe Mode''' (not Refresh)&#46; Did this help? While you are in safe mode; Try disabling graphics hardware acceleration in Firefox&#46; Since this feature was added to Firefox it has gradually improved but there are still a few glitches&#46; ''[https://support&#46;mozilla&#46;org/en-US/kb/forum-response-disable-hardware-acceleration How to disable Hardware Acceleration]'' {web link}