IIS 7 Error “A specified logon session does not exist. It may already have been terminated.” when using https

Question

I am trying to create Client Certificates Authentication for my asp.net Website.

In order to create client certificates, I need to create a Certificate Authority first:<

Answer 1

In my case I imported a newer version of a certificate (PFX for IIS) from StartSSL just recently and forgot to remove the old one, which somehow caused this error (now two certs sort of the same). I removed both of them, imported the proper one, and now it works.