CGD Computing FAQs

Adding, Deleting and Accepting SSL Certificates in Firefox


You go to a web page and get a warning or error stating the web address you are connecting to "uses an invalid security certificate" and you are unable to view the web page.


What is going on?

  • The server certifcate could have expired or changed.
  • Someone could be trying to impersonate the server or you were directed to a wrong web page

The Fix:

  • First check to make sure that the warning refers to the web site you are intending to visit. (See red arrow below). The first line on the Secure Connection Failed page will tell you the web page you were connecting "uses an invalid security certificate"

  • If the page is correct, an exception can be added to your web browser to allow access. Click on the link at the bottom of the page that says "Or you can add an exception..."

  • Click "Add Exception"
  • On the next window click "Get Certificate"

  • At this point you should click on "View" to view the certificate and double check that it contains information you expect to see. i.e. check that the Common Name and Organization are what you expect.

  • If all looks well, go ahead and click "Close" and then click "Confirm Security Exception". At this point you should be re-directed to the page you were trying to reach.

I Don't get the option to Add an Exception:

  • If you do not get the "Or you can add an exception..." option, you will need to delete your old certificate because the certificate has changed. To delete in Firefox:

Windows: Go to the "Tools" pull down menu and select "Options"
Linux: Go to the "Edit" pull down menu and select "Preferences"
Macintosh: Go to the "Firefox" pull down menu and select "Preferences"

  • Click on the "Advanced" option tab and then click on "Encryption".

  • Click on the "Servers" tab and find the server you are having trouble connecting to and delete the certificate by clicking on "Delete".

  • At this point the certificate is deleted and you will need to connect to the web page again and follow the instructions above to get the certificate.

Send an email to the if you have any problems or questions.