with avast blocking/scaning https, firefox reports that ALL the certificates are not valid
this i a known and old issue, why it was not fixed?
anyone? the only “fix” is to disable https control 
I use firefox and https just fine, I’m not sure what particular “known issue” you’re referring to. I’ll try and offer some advice if I can though.
Perhaps lets start with the basics, like Windows version, Firefox version, Avast version etc. Do you have any screenshots you can share? Is it happening on all computers or just some? All https sites or just a selection of sites? Do other browsers have the same problems? Have you contacted support for advice?
Desperados,
what exact version of AES are you using ?
I’m using Avast for Business (cloud)
https://www.dropbox.com/s/80pbih3o0vshfwy/Screenshot%202017-06-05%2009.10.29.png?dl=0
no problems with IE11
it seems that the problem happens only on some computers
I’ve this problem when the date/time(zone) on the system was not (entirely) correct.
Another solution that should work is setting up Firefox to work with the vast certificate.
Several links on the Mozilla website (ok and one on ehow ;D ):
http://www.ehow.com/how_11385212_troubleshoot-reset-connection-firefox.html
https://support.mozilla.org/en-US/kb/server-not-found-connection-problem
https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can
https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message
https://support.mozilla.org/en-US/kb/connection-untrusted-error-message
http://kb.mozillazine.org/Error_loading_websites
mmm where can I found it? tks
EDIT: I found digicert_ca_77.der in avast folder, but it doesn’t fix the problem
Windows date and time are ok
No clue where to find as I don’t use FireFox.
It is mentioned several times on the Mozilla support site.