This problem of showing web pages untrusted can occur due to many reasons. But in most of the case it occurs when the browser misinterprets SSL Certificate of the website. Try updating your date and time of your system, I hope this will solve the issue.

System date and time is fine. Next suggestion?

hello, a possible solution depends on different factors:

• what is the error code shown under technical details on the error page?

in case the error code equals sec_error_unknown_issuer, please attempt to add an exception on the bottom of the error page & inspect the certificate (see the screenshot attached for instructions):

• which issuer information does the certificate contain?

thank you!

"This Connection is Untrusted" error message appears - What to do

I do not get an option of adding an exception I do not get 'I understand the risk' It just stops at Technical Details Here is an example:

This Connection is Untrusted

You have asked Firefox to connect securely to mail.google.com, but we can't confirm that your connection is secure.

Normally, when you try to connect securely, sites will present trusted identification to prove that you are going to the right place. However, this site's identity can't be verified. What Should I Do?

If you usually connect to this site without problems, this error could mean that someone is trying to impersonate the site, and you shouldn't continue.

Technical Details: mail.google.com uses an invalid security certificate. The certificate is not trusted because no issuer chain was provided. (Error code: sec_error_unknown_issuer)

No option to add exception

which antivirus program are you using?

please also go to your system control panel and remove anything named Sendori, BrowserSafeguard, BrowserSafe, SafeGuard or other software that sounds suspicious and didn't get installed by you intentionally.

in addition run a full scan of your system with different security tools like the free version of malwarebytes and adwcleaner.

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button and inspect the certificate and check who is the issuer of the certificate.

You can see more Details like intermediate certificates that are used in the Details pane.

If "I Understand the Risks" is missing then this page may be opened in an (i)frame and in that case try the right-click context menu and use "This Frame: Open Frame in New Tab".

• Note that some firewalls monitor (secure) connections and that programs like Sendori or FiddlerRoot can intercept connections and send their own certificate instead of the website's certificate.
• Note that it is not recommended to add a permanent exception in cases like this, so only use it to inspect the certificate.

Removing BrowserSafeguard fixed the problem. I don't know how that got on my computer but it's better now.

Thanks!