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-----