Right-click on browser.xul.error_pages.expert_bad_cert and select Toggle. The value will change to true.

Question

I am working with Firefox 30. I get a certificate error on each webpage I go to. I have reset and uninstalled the browser to no luck. I have also did the following:
Open a new Firefox window, and type this into the address/URL:
about:config
- You'll probably see a warning that changing the config can be dangerous. Click the button to accept the warning and proceed, but BE CAREFUL from here on!
- A table will appear showing various Firefox settings ("Preference Names") and their current values.
- In the Filter box type: broswer.xul
- There should now be a shorter list of settings, including one named browser.xul.error_pages.expert_bad_cert with a value of false.
- Right-click on browser.xul.error_pages.expert_bad_cert and select Toggle. The value will change to true.
- Exit completely from Firefox (i.e. close all windows), and then restart it.
This has not worked either. Does anyone have any other thoughts?

Answer 1

Any idea why you are getting these errors?
If you expand the technical details section of the error page, there should be some kind of explanation or code there. Can you copy/paste that into a reply?
If it says something along the lines of "sec_error_unknown_issuer" this can indicate one of these situations:
(1) Incomplete security software installation
Some security suites include a feature to intercept and scan your web traffic, including secure connections. In order to do this, they must present a fake certificate to Firefox, which of course, Firefox rejects. Programs such as ESET and Kaspersky provide a way to either turn off this feature, or import a master certificate into Firefox so that Firefox will trust these programs.
Does that sound relevant?
(2) Malware
Unfortunately, some malware also will intercept your secure connections. Often they can do this invisibly in IE and Chrome because they can inject certificates into the shared Windows certificate store. Because Firefox uses its own certificate file, you may get errors in Firefox that you do not get in IE and Chrome.
To distinguish these, it's helpful to inspect the "Issued by" section of one of the certificates from a site that works in IE but not Firefox.
When you get the error page in Firefox, you can expand the "I understand the risks" section, and click the button to Add Exception. You don't need to actually save an exception to inspect the certificate, so you can cancel after viewing the certificate.
Check the "Issued by" section to see what you find there. For example:
* Name associated with your security software, such as ESET, BitDefender, Kaspersky, etc.
* Sendori (indicates unwanted software from Sendori)
* FiddlerRoot (indicates unwanted software named similarly to BrowserSafeguard, BrowserSafe, SafeGuard)
* Something else
What do you see?