If you select "Never remember history" or the combination of "Use custom settings for history" + "Always use private browsing mode" then Firefox restarts in a completely private session. Extensions have a separate setting for whether they are allowed to run in private windows. More info in this article: Extensions in Private Browsing. Was that the issue?

Hi Jscher2000 it is only selecting "Never remember history" and if I revert the choice then the add-on are back.

If you do prefer automatic private browsing, you should be able to set your extension to run in private windows. Or didn't that work?

It works yes but it is a counter measure, not the normal behavior. I want to be able to select "Never remember history" and see my add-ons working.

Okay, did you set each extension to have permission to run in private windows, and then test again? Extensions in Private Browsing

Yes it works but again it is odd. Did you face that strange behavior too ?

Note that there is this pref on the about:config page that is false by default.

• extensions.allowPrivateBrowsingByDefault

Yes it works but again it is odd. Did you face that strange behavior too ?

What is odd? I use normal browsing and just open private windows when needed, so I'm not familiar with the ins and outs of automatic private browsing.