Hi, sorry. Norton should not have issues with Firefox and their Support Forum would have helped you. I am a ex Beta Tester and Norton User, There are no issues. I never have problems. A Biased user : NORTON INTERNET SECURITY

Kaspersky has had issues for far longer and constantly.

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connections and send their own certificate. This causes problems monthly.

Please let us know if this solved your issue or if need further assistance.

Actually I would say I have seen more reported issues overall over the years here and at mozillaZine with Norton whether it comes to the extensions they try to install in Firefox or with false positives on a variety of Firefox things in program. Though Norton did in the past win in often being the fastest with extension updates for each new major Firefox Release.

Norton has been bad with Thunderbird and SeaMonky at times also with false positives. The SeaMonkey community has singled out Norton/Symantec for several years now due to Symantec not fixing certain false positives as you can see a mention in known issues on https://www.seamonkey-project.org/releases/seamonkey2.49.3/

Whatever antivirus client you use you should consider not using the antivirus provided extensions. https://www.howtogeek.com/239950/dont-use-your-antivirus-browser-extensions-they-can-actually-make-you-less-safe/

Any antivirus clients that cause issue with secure connections in Firefox is because they have a certain setting enabled by default instead of off by default. Problem is many less technical users think they would be less safe if they disable that feature and think the Firefox browser should somehow ignore or workaround the problem instead.

The common problem some antivirus clients can cause with secure connections is https://support.mozilla.org/en-US/kb/troubleshoot-SEC_ERROR_UNKNOWN_ISSUER

thanks PKshadow. I was a long-time Norton user, but their password manager quit on Firefox about 2 years ago. That pissed me off enough that I switched to Kaspersky, on the advice of some IT guys I know. Didn't have any issues until Firefox 58, I think, then Kaspersky started acting up. Now their android client doesn't support Firefox for android, so here I am again, looking for other options... that don't involve Chrome.

Password Manager is back : https://addons.mozilla.org/en-US/firefox/search/?platform=windows&q=norton

James, Thank you for the info... I checked the link about the a/v extensions. very interesting.

Comodo Antivirus 10 is what I recommend. That is the 'free for personal use' version and doesn't come with any stupid Firefox extensions that no AV / security suite can seem to keep working and updated properly. And those stupid extensions for Firefox usually duplicate features that are already in Firefox.