I run FF 52.4.1 ESR 64 bit
I run windows 10 Home US English 64 bit
Bitdefenter Total security 5 devices 2018 version
Superantispyware 6.0.1250 Pro
Advanced Systen care 10.5 pro
Your connection is not secure
The owner of http://www.google.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.
This site uses HTTP Strict Transport Security (HSTS) to specify that Firefox may only connect to it securely. As a result, it is not possible to add an exception for this certificate.
Learn more…
How to troubleshoot the error code "SEC_ERROR_UNKNOWN_ISSUER" on secure websites
On websites which are supposed to be secure (the URL begins with "https://"), Firefox must verify that the certificate presented by the website is valid. If the certificate cannot be validated, Firefox will stop the connection to the website and show a "Your connection is not secure" error message instead. This article explains why you might see the error code "SEC_ERROR_UNKNOWN_ISSUER" on websites and how to troubleshoot it.