Playing around with ASP.net MVC on Mono and the Facebook API Login for Server-side Apps the System.Net.WebClient threw a TslException with the message: "Invalid certificate received from server. Error code: 0xffffffff800b010a".
After that, I experimented importing all general certificates using
$ mozroots --import --ask-remove
But the error still occurred so that importing the needed certificates directly by defining the URL using the
certmgr solved the problem.
$ certmgr -ssl https://facebook.com