Mozilla Firefox: "This connection is untrusted." + SSL Certificate + Cpanel

When you browse to a secure website using Mozilla Firefox, you may encounter the message: "This connection is untrusted."  Google Chrome and Microsoft Internet Explorer may not display a warning.  They may in fact display icons and related in...

When you browse to a secure website using Mozilla Firefox, you may encounter the message: “This connection is untrusted.”  Google Chrome and Microsoft Internet Explorer may not display a warning.  They may in fact display icons and related information stating the channel is secure.  You may observe that other computers using Firefox do not display the message: “This connection is untrusted.”

There are numerous reasons for encountering the message: “This connection is untrusted.”  An example of this would be an expired SSL Server Certificate.  However, you may find the issue is due to missing Intermediate Certificates in the SSL Chain.  The missing Intermediate Certificates may be the RSA Domain Validation Secure Server Certificate and the RSA Certification Authority Certificate.  On Windows computers, Google Chrome and Microsoft Internet Explorer use the Trusted Root Certification Authorities Store on the client computer to obtain the Intermediate Certificates in the SSL Chain.  Firefox uses the Mozilla CA Certificate Store and retrieves the Intermediate Certificates from the Internet when it has not been previously cached.  When cached from other websites, the Intermediate Certificates are present and the message “This connection is untrusted” is not displayed.

To install an SSL Server Certificate, you normally select your SSL Server Certificate in Cpanel and then click Install Certificate.  Upon installing your SSL Server Certificate, Cpanel then normally fetches the Intermediate Certificates from a public repository.  The SSL Channel is then activated and everything appears to be normal.  If you are using Cpanel, you may find the SSL Channel is active but the Intermediate Certificates have not been installed.  To resolve this issue, please perform the following steps:

Re-Keying SSL Server Certificate in Cpanel

  1. Email your Certificate Authority and obtain their current CA-Bundle.
  2. Make a manual backup of all SSL Certificate Information in your Cpanel SSL/TLS Manager.
  3. After completing a manual backup of all SSL Certificate information (not outlined here), browse to your Cpanel SSL/TLS Manage.
  4. Click Certificates and delete the SSL Server Certificate.  (Clicking Update to update the certificate with the CA-Bundle information does not work so you will have to Delete.)
  5. After certificate deletion, click the Return To SSL Manager button.
  6. Click Activate SSL on Your Web Site (HTTPS) and then click Uninstall next to the SSL Server Certificate you wish to uninstall.
  7. After uninstallation, click your Browser Back Button.
  8. Click Certificates and browse to your CRT file and then click Upload Certificate.
  9. After upload, click the Return To SSL Manager button.
  10. Click Activate SSL on Your Web Site (HTTPS) and then click Browse Certificates.  Then click Use Certificate.
  11. The Certificate (CRT) field and the Private Key (KEY) fields are then auto-filled.  In the last field labeled Certificate Authority Bundle (CABUNDLE) Optional, paste the CA-Bundle text.
  12. Click Install Certificate.

This issue has been resolved.

To confirm this, I recommend the following online tools:

https://www.geocerts.com/ssl_checker

https://www.ssllabs.com/ssltest/analyze.html

https://sslanalyzer.comodoca.com/ 

https://www.sslshopper.com/ssl-checker.html