Updating FireFox to version 33 breaks SSL connectivity with certificates signed by our company's internal CAs. As of the latest update, we get the following error message with no method of override: An error occurred during a connection to www.google.com. security library: improperly formatted DER-encoded message. (Error code: sec_error_bad_der) I assume the problem stems from the new mozilla::pkix certificate validation. The sec_error_bad_der seems to indicate there's a parsing issue with the certificate itself. These certificates work fine in FF <32, Chrome, and MS IE. But I recognize there may be something subtly wrong with these certs that should be corrected. However, FireFox doesn't actually give any useful information to help troubleshoot this. What options are available to discover what exactly FF is finding so broken about these?