After changing the SSL decryption certificate on the Palo Alto Networks firewall, SSL Decryption does not work for the Firefox browser.
The Firefox browser shows a certificate error, while SSL decryption for other web browsers continue to work.
The Firefox browser saves cookies in its cache.
Removing the cookies for the particular websites that produce the certificate errors will resolve the issue. On Firefox, cookies can be removed from the Privacy settings.
Note: Please refer to the Mozilla Firefox support site https://support.mozilla.org for more information about the removing cookies.
Here is one article from their site that might help: