Make STARTTLS error messages better

* lisp/net/network-stream.el (network-stream-open-starttls):
Output a better error message when TLS negotiation fails while
doing STARTTLS (bug#23027).

1 files changed, 3 insertions, 0 deletions

diff --git a/lisp/net/network-stream.el b/lisp/net/network-stream.el
index 5ddaef58a89..c2845d96a5d 100644
--- a/lisp/net/network-stream.el
+++ b/lisp/net/network-stream.el
@@ -312,6 +312,9 @@ gnutls-boot (as returned by `gnutls-boot-parameters')."
                                         :host (puny-encode-domain host)
                                         :service service))
             (network-stream-get-response stream start eoc)))
+        (unless (process-live-p stream)
+          (error "Unable to negotiate a TLS connection with %s/%s"
+                 host service))
         ;; Re-get the capabilities, which may have now changed.
         (setq capabilities
               (network-stream-command stream capability-command eo-capa))))