HTTPS site certificates do not show full certificate chain of trust.
When I visit an HTTPS site that is signed by an Intermediate CA that is not yet in the Authorities list, the site comes up as untrusted. When I click on Add Exception, then click on the View button to view the certificate, and then go to the Details tab, the full certificate hierarchy is missing and only the issued certificate shows up. If I view the same certificate using Internet Explorer, I see the full hierarchy. Using https://share.ps.net as an example: GTE CyberTrust Global Root
Dell Inc. Enterprise CA Dell Inc. Enterprise Issuing CA1 share.ps.net
But in FF, I only see share.ps.net in the heirarchy.
Opaite Mbohovái (1)
That website doesn't send a full certificate chain and if you haven't visited a website before that sends them then you get the untrusted connection error.
You can visit this Dell website to make Firefox store those needed certificates.
No need to save anything yourself.