Sounds more like Norton issue then Firefox. Maybe contact Norton support about issues with their software that needs updating.

Please look at the attached jpeg. I get this error everytime I open Firefox. Can you help stop this error.

What Extensions do you have installed in Firefox?

If I go to https://addpns.browse-privately.net/ it says they have a "browse privately" extension on the addons.mozilla.org yet I cannot find one. It's possible it has been added to extension blocklist for some reason?

https://support.mozilla.org/en-US/kb/add-ons-cause-issues-are-on-blocklist

I contacted Norton's and the issue is theirs. They are fixing Norton's Antivirus and told me I will not see the error anymore. Below is the case they created for the issue.

Hello , Request for file re-evaluation has been received. Please use request Id ccc90751-970a-431f-8931-56fa0ad0585d for checking the status of your submission. Further details for your submission can be found here.

Thank you! Norton Safe Web

Doug