https://community.norton.com/en/forums/firefox-40-support-norton-toolbar-0 https://community.norton.com/en/blogs/product-update-announcements/firefox-40-support-norton-toolbar

The Norton toolbar still works in Firefox if you have updated it from Norton. It just gives a warning that it is not signed.

Update Norton, https://community.norton.com/en/blogs/product-update-announcements/firefox-40-support-norton-toolbar

Note that the Norton browser add-ons are basically useless for increasing your security and simply replicate features already in Firefox. They do not impact the actual anti-virus running on your computer. You can remove them without harm.

djdupont said

Firefox version 40.0.2 does not permit Norton Security Safe as an "add-on." I NEED Norton to work with Firefox. The previous version of Firefox worked well with Norton, and I want to reinstall that earlier version. How do I get that version?

Norton has a new update where their Norton Extension is verified so do Live updates in Norton. https://community.norton.com/en/comment/6602061#comment-6602061