Failing to Import Root CA Certificates to Mozilla Firefox

This section provides a tutorial example on how to import a root CA certificate into Mozilla Firefox. The import process failed with an error.

If I don't want to add a security exception to trust the Yahoo site when Firefox gives me the "Your Connection is not secure" error, I need to fix the error.

Since I know the root cause of this error is missing the root CA certificate, I can try to fix by importing the root CA certificate "DigiCert High Assurance EV Root CA" back into Mozilla Firefox from the certificate file I created earlier.

1. Repeat steps listed in the previous tutorial until you see the

2. Click the "Authorities" tab, since I want to import a CA (Certificate Authority) certificate.

3. Click the "Import" button. The "Select File containing CA certificate(s) to import" dialog box shows up.

4. Find and select \temp\DigitCer_Root_CA_pem.crt, which contains the "DigiCert High Assurance EV Root CA" certificate I created earlier.

7. Click the "Open" button to let Firefox import the certificate. Surprisingly, I got an error message box saying that "This certificate already installed as a certificate authority."

Why I am getting this error? I remember I deleted "DigiCert High Assurance EV Root CA" certificate from Firefox. Read the next section to find out the answer.

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