--- a/jdk/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/Stream.java	Thu Jun 08 12:24:13 2017 +0100
+++ b/jdk/src/jdk.incubator.httpclient/share/classes/jdk/incubator/http/Stream.java	Thu Jun 08 12:41:07 2017 +0100
@@ -803,7 +803,9 @@
         completeResponseExceptionally(e);
         try {
             // will send a RST_STREAM frame
-            connection.resetStream(streamid, ResetFrame.CANCEL);
+            if (streamid != 0) {
+                connection.resetStream(streamid, ResetFrame.CANCEL);
+            }
         } catch (IOException ex) {
             Log.logError(ex);
         }