network-stream-get-response returns nil if the server connection is lost, hence network-stream-command does the same. There was one instance of a blind string-match against the return value which would fail with a STRINGP NIL error from time to time. The attached patch fixes this. 2013-02-13 Didier Verna * net/network-stream.el (network-stream-open-starttls): Check that the response to the starttls-command is not nil before string-match'ing it.