Firefox – Mozilla Firefox won’t connect to Google, IE can

certificatefirefoxgoogle-searchinternet explorerSecurity

I have went on to Google search before, however today, Mozilla Firefox won't let me connect to Google's search page.

This is what I get.

You have asked Firefox to connect securely to www.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.

This site uses HTTP Strict Transport Security (HSTS) to specify that
Firefox only connect to it securely. As a result, it is not possible
to add an exception for this certificate.

www.google.com uses an invalid security certificate.

The certificate is not trusted because the issuer certificate is
unknown. The server might not be sending the appropriate intermediate
certificates. An additional root certificate may need to be imported.

(Error code: sec_error_unknown_issuer)

I tried uninstalling and resetting Firefox but I still get the same message.
(Also Internet Explorer opens the page just fine.)

UPDATE: Only one user out of the three on the computer doesn't have this problem.

Best Answer

Firefox is protecting you from what it thinks is a man-in-the-middle attack, where some other program is intercepting and possibly altering your communications with Google. It's possible that your connection is actually being hacked, but another common possibility is that you (or your employer) has a firewall which inspects and possibly alters your web traffic for legitimate reasons. In that case, you would need to tell Firefox to allow that interception, by installing the firewall's certificate in Firefox's trust list.

You have a couple of options:

  • Ask your system administrator or IT department, if you have one. They will be able to confirm that this should be happening, give you a copy of the certificate, and perhaps help you install it into Firefox (usually under Preferences > Advanced > Certificates but it varies by version).
  • View the Google certificate in the error dialog that Firefox shows. It will have a "Subject" (which should be Google) and an "Issuer" (which, for the real Google, is GeoTrust via an intermediate Google certificate, but for a firewall will probably be named after the firewall vendor). If you recognize this issuer as legitimate, you can find the certificate in Windows' trust list, export it, and then import it into Firefox's list of trusted certificate authorities.

Firefox, for historical reasons, has its own trust list separate from Windows', but IE uses the Windows list. It sounds like the intercepting certificate is in Windows' trust list and in one user's Firefox list but not in other users' lists.

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