Hi YrmMerkstave, I'm surprised that Firefox would come with different "root" certificates in different locales.

In your working Firefox, you can check in the Certificate Manager, Authorities tab, to see whether the critical certificate is marked as "Builtin" or "Software Security Device" -- the latter are those collected and cached by Firefox as you browse.

Is it possible that the server is not sending one or more "intermediate" certificates needed to connect the site certificate with the root certificate? Those are usually provided in a bundle file, or could be downloaded from your certificate issuer separately.

You can check for any "chain issues" on a test site such as the following: https://www.ssllabs.com/ssltest/

Hi, if I access the sisal.it (the site included vetrina.gntn-pgd.it) site with the windows version there are no problems but if I access with the linux version Firefox starts blocking the browsing adducing problems with the certificates. I attach images. What do i do? Bye.

Hi tonylab, if you click the Avanzate button, Firefox should show more details about the error including a CODE_IN_CAPITAL_LETTERS. This article has more information on those codes. Does anything here help:

How to troubleshoot security error codes on secure websites

To transfer cached intermediate certificates you can copy cert9.db from one profile to another profile.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

• cert9.db (58+) or cert8.db (57 and older) for (intermediate) certificates stored in the Certificate Manager
  if you only have cert8.db then make sure to remove an existing cert9.db