Mozilla Firefox Displaying Certificate Error Page

This section provides a tutorial example showing that Mozilla Firefox fails to validate an HTTPS server certificate and displays a certificate error page.

Now I want to see how Mozilla Firefox behaves after I deleted the root certificate "VeriSign Class 3 Public Primary Certification Authority - G5".

1. Open Mozilla Firefox to visit "https://login.yahoo.com".

2. Mozilla Firefox returns with an untrusted connection error page:

Certificate Error Page - Mozilla Firefox
Showing Certificate Validation Error in Mozilla Firefox

3. Read the error message:

This Connection is not secure

The owner of login.yahoo.com has configured their website improperly. To
protect your information from being stolen, Firefox has not connected to
this website.

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

Mozilla Firefox fails to validate "login.yahoo.com" certificate as expected, because the root CA "VeriSign Class 3 Public Primary Certification Authority - G5" certificate has been deleted from Firefox.

See next tutorials on how install the root CA back, or add an security exception to continue using the Website.

Table of Contents

 About This Book

 Introduction of PKI (Public Key Infrastructure)

 Introduction of HTTPS (Hypertext Transfer Protocol Secure)

 Using HTTPS with Google Chrome

Using HTTPS with Mozilla Firefox

 Visiting "https" Website with Mozilla Firefox

 Viewing Server Certificate in Mozilla Firefox

 Server Certificate General Information

 Viewing Server Certificate Path in Mozilla Firefox

 Exporting Server Certificate to File in Mozilla Firefox

 Viewing Pre-Installed Certificates in Mozilla Firefox

 Listing of Trusted Root CA in Mozilla Firefox

 Exporting Certificate to File from Mozilla Firefox

 Deleting Root CA Certificates from Mozilla Firefox

Mozilla Firefox Displaying Certificate Error Page

 Adding Security Exception in Mozilla Firefox

 Failing to Import Root CA Certificates to Mozilla Firefox

 Certificate Trust Settings in Mozilla Firefox

 HTTPS with Microsoft Edge

 Using HTTPS with Apple Safari

 HTTPS with IE (Internet Explorer)

 Android and Server Certificate

 iPhone and Server Certificate

 Windows Certificate Stores and Console

 RDP (Remote Desktop Protocol) and Server Certificate

 macOS Certificate Stores and Keychain Access

 Perl Scripts Communicating with HTTPS Servers

 PHP Scripts Communicating with HTTPS Servers

 Java Programs Communicating with HTTPS Servers

 .NET Programs Communicating with HTTPS Servers

 CAcert.org - Root CA Offering Free Certificates

 PKI CA Administration - Issuing Certificates

 Comodo Free Personal Certificate

 Digital Signature - Microsoft Word

 Digital Signature - OpenOffice.org 3

 S/MIME and Email Security

 PKI (Public Key Infrastructure) Terminology

 Outdated Tutorials

 References

 Full Version in PDF/EPUB