NET::ERR_CERT_AUTHORITY_INVALID-yes, have read other posts on it.STILL happning

[REDACTED]

Using OSX 10.9.5. Can't update yet as I use some programs that won't work in High Sierra. This is happening on MANY sites for me in Chrome; same error message. I have Avast antivirus and the Avast Chrome extension and have scanned for issues-nothing is found. I cannot use many sites I've been using for years. Like this one:
Subject: www.tacobell.com

Issuer: Avast untrusted CA

Expires on: Feb 15, 2019

Current date: May 9, 2018

PEM encoded chain:
-----BEGIN CERTIFICATE-----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==
-----END CERTIFICATE-----

[ondrej.kolacek]

Hello,

first, the following is >>ONLY RELEVANT<< on OSX 10.9.

It seems that verification of https certificates on OSX 10.9 itself (nothing to have in common with anything Avast software does) somehow got broken. When we have released Avast 13.5 all used to work correctly but when testing 13.6 we have found out that something went wrong.

For instance even without Avast webshield running, or even without Avast installed at all, certain web pages stopped working correctly not only on Safari, but we believe that during the testing they also stopped working in Chrome and Firefox. However it seems that both Chrome and Firefox have since fixed the issue. Safari still behaves as it was during the tests - it pops up "untrusted certificate" popup and requires user to accept the certificate before allowing the page to show. Please note that this is Mac OS X OS failing to verify completely valid certificates via the code which used to work for years and works in all other versions of the OS.

This broke both the old Avast 13.5 and the new 13.6 and 13.7.

We will be pushing have pushed out an online update within few hours which will temporarily disable webshield for Firefox and Chrome on 10.9. This will give us time to make a more fine-grained solution in the next version coming out hopefully within a week. Please wait for Avast update to run automatically (or update manually with possible turning webshield off and on afterwards being necessary) and both Chrome and Firefox should work again.

We apologize for the issue and thank you all for reporting bugs, especially on less common versions of MacOS.

Kind regards,
Ondrej Kolacek