ALPN protocol selected.
+=item SSL_TLSEXT_ERR_ALERT_FATAL
+
+There was no overlap between the client's supplied list and the server
+configuration.
+
=item SSL_TLSEXT_ERR_NOACK
-ALPN protocol not selected.
+ALPN protocol not selected, e.g., because no ALPN protocols are configured for
+this connection.
=back