Firefox Dev Ed: No internet alert but mozilla.org works

[conticreative]

I just downloaded and installed Firefox Developer Edition on both my Laptop and my desktop. Both machines have windows 10, one has Kaspersky, the other Avast and they are both updated and in good working conditions.
I first navigated around the mozilla.org website to read a bit more about the dev. build. Then I tried logging into Firefox with my alternate account (my regular one has too many extensions for developing ) and I received an error that I had no internet connection at the sign in page.

Weird. So I tried navigating to another website, including google.com, yahoo.com and several minor sites. None of them worked and FF Dev claimed their certificate was untrustworthy.

My regular Firefox still works fine on both machines, as do my other browsers. However, Firefox Dev. Edition keeps telling me it cannot connect to any site because of the certificate issue. Sites that don't have a certificate, load fine, but no secure site, except mozilla.org (BUT excluding Firefox's own sign in screen) loads, either because of the certificate error or because it claims I have no Internet connection (I do, naturally and I can reach mozilla just fine).

Since it behaves identically on 2 machines that share little in terms of AV, firewall, etc. I have to surmise this is an issue with the Dev edition.

By the way, I tried to create an exception for those sites (like Google) but it won't let me. In the error page it tells me that the error is:

SEC_ERROR_UNKNOWN_ISSUER

and there is no way to create a manual override that I can see. It would also be a royal pain to do it for every secure site.

I searched extensively for a solution, but whenever I found a promising post on https://support.mozilla.org first it takes forever to load (when it does) when it loads there seem to be no CSS loaded, and finally, those few posts that seemed to deal with the issue, were old and treated it from the viewpoint of a website who's certificate had expired and how to make an exception.
That's not the issue I am having. I fairly sure Google.com has a valid certificate and regular firefox has no trouble with it.

I can survive without FDE, but it is disappointing. Should I just uninstall and wait until things settle down?

[GHM113]

The problem is in Kaspersky. I have exactly the same problem every time I install new Firefox browser including Firefox Release, Beta, Dev Edition and Nightly or try to create a new browser profile for any of those browsers. The source of the problem is that Kaspersky intercepts ALL HTTPS traffic on your computer. In order to do that it has to import its own Kaspersky sertificate into Firefox certificate storage. But for some reason sometimes it might take a long time - in my own experience, even a couple of days.

You have 3 options:
1. Wait (it might be enough to reload Firefox or OS)
2. Contact Kaspersky support
3. Use a tip from this thread:
https://forum.kaspersky.com/index.php?showtopic=351476

For now I just disabled "Scanning of encrypted connections" in KIS settings

or post #2 from the same thread.

[JayhawksRock]

Same using Windows Explorer or not ?
https://encrypted.google.com/search?sit ... 2aLGt_2eCM