If you're using Linux, you can also follow this official wiki pages:

• Configuring SSL certificates on Linux.
• NSS Shared DB And LINUX
• NSS Shared DB Howto

Basically:

• click the lock icon with an X,
• choose Certificate Information
• go to Details tab
• Click on Export... (save as a file)

Now, the following command will add the certificate (where YOUR_FILE is your exported file):

certutil -d sql:$HOME/.pki/nssdb -A -t "P,," -n YOUR_FILE -i YOUR_FILE

To list all your certificates, run the following command:

certutil -d sql:$HOME/.pki/nssdb -L

If it still doesn't work, you could be affected by this bug: Issue 55050: Ubuntu SSL error 8179

P.S. Please also make sure that you have libnss3-tools, before you can use above commands.

If you don't have, please install it by:

sudo apt-get install libnss3-tools # on Ubuntu
sudo yum install nss-tools # on Fedora, Red Hat, etc.

As a bonus, you can use the following handy scripts:

$ cat add_cert.sh
certutil -d sql:$HOME/.pki/nssdb -A -t "P,," -n $1 -i $1
$ cat list_cert.sh
certutil -d sql:$HOME/.pki/nssdb -L # add '-h all' to see all built-in certs
$ cat download_cert.sh
echo QUIT | openssl s_client -connect $1:443 | sed -ne '/BEGIN CERT/,/END CERT/p'

Usage:

add_cert.sh [FILE]
list_cert.sh
download_cert.sh [DOMAIN]

Troubleshooting

• Run Chrome with --auto-ssl-client-auth parameter

  google-chrome --auto-ssl-client-auth

getting-chrome-to-accept-self-signed-localhost-certificate