Hi Pete, the specific error code you got is pretty unusual:

SEC_ERROR_OCSP_INVALID_SIGNING_CERT

Could you check the other error pages and see whether you are getting that one about INVALID OCSP or a more common one such as UNKNOWN ISSUER? That hopefully will help lead us to a solution.

Meanwhile, here's my general spiel on certificate errors in Firefox:

When you get untrusted connection errors for pretty much all secure sites, the problem usually is one of the following:

(1) Error in your system's date, time, or time zone, which throws off certificate validity checks. Sometimes allowing computers to use an internet-based time source can introduce this problem.

(2) Firefox not being set up to work with your security software that intercepts and filters secure connections. Products with this feature include Avast, BitDefender, Bullguard, ESET, and Kaspersky; AVG LinkScanner / SurfShield can cause this error on search sites.

(3) On Windows 10, Firefox not being set up to work with the parental control software Microsoft Family Safety. (To test by turning it off, see: http://windows.microsoft.com/en-us/wi.../turn-off-microsoft-family-settings)

(4) Malware on your system intercepting secure connections.

If you have any of those specific security products:

That would be the first thing to check. This support article will walk you through it: How to troubleshoot security error codes on secure websites.

If none of those ring a bell:

You could inspect a sample certificate to see whether that points to the culprit. If you want to try that now, here's how I suggest starting:

Load my test page at: https://jeffersonscher.com/res/jstest.php

You likely will get an error page. Expand the "Advanced" button and look for an Add Exception button.

Note: You don't need to complete the process of adding an exception -- I suggest not adding one until we know this isn't a malware issue -- but you can use the dialog to view the information that makes Firefox suspicious.

Click Add Exception, and the certificate exception dialog should open.

Click the View button. If View is not enabled, try the Get Certificate button first.

This should pop up the Certificate Viewer. Look at the "Issued by" section, and on the Details tab, the Certificate Hierarchy. What do you see there? I have attached a screen shot for comparison.

Try to rename the cert8.db file (cert8.db.old) and delete the cert_override.txt file in the Firefox profile folder to remove intermediate certificates and exceptions that Firefox has stored.

If that has helped to solve the problem then you can remove the renamed cert8.db.old file. Otherwise you can rename (or copy) the cert8.db.old file to cert8.db to restore the previously stored intermediate certificates. Firefox will automatically store intermediate certificates that servers send in the Certificate Manager for future use.

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thanks for Your good answers!!

unfortunately they didn´t help to me. Funny thing happened when I got this first error-message and after it I klick "read more" I got error message:"SEC_ERROR_OCSP_FUTURE_RESPONSE" to site " support.mozilla.org".

But back to topic... I rename cert8.db to cert8.db.old but I didn´t have file cert_override.txt file in my computer. This is brand new and I haven´t surf it avywhere else than ixquick.com. So there is no history in this computer. Or exceptions.

One good feature is tab where I can write my own exceptions of certified sites. Like older versions.

My computer has McAfee at virus software. All firewalls are shutted down and now McAfee has shutted down as well. So I think nothing unusual can´t disturb internet traffic.

I still have my Plan-B: v3.0.6.

hi, FUTURE_RESPONSE indicates that there is something wrong with your system clock. please double-check that you have set the right date, time & timezone! http://time.is

Hello !!

So, it was date wicth was "incorrect". Usually I keep my date one day later than normally, because of trojan. If something is scheduled I have one day time to react.

I understand why add feature like this to web browser. But still I miss simply standard hyper text format. http is made for open document sharing. And that´s what I use. I like idea to have possibility to choose witch I want to use: stadard or secure browsing.

I might be dinosaur but...

Hi Pete, more and more sites are switching from HTTP to HTTPS because it protects against snooping on many of the details of your browsing by those between your computer and the server. For example, many search sites use HTTPS even if you are not logged in. Also, this forum uses HTTPS for all visitors. It doesn't have anything to do with being open or not; that's a separate issue for sites to decide.