Index: trunk/src/org/openstreetmap/josm/gui/oauth/OsmOAuthAuthorizationClient.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/oauth/OsmOAuthAuthorizationClient.java	(revision 9902)
+++ trunk/src/org/openstreetmap/josm/gui/oauth/OsmOAuthAuthorizationClient.java	(revision 9904)
@@ -195,4 +195,5 @@
             return null;
         }
+        Main.warn("No authenticity_token found in response!");
         return null;
     }
@@ -200,7 +201,8 @@
     protected SessionId extractOsmSession() {
         List<String> setCookies = connection.getResponse().getHeaderFields().get("Set-Cookie");
-        if (setCookies == null)
-            // no cookies set
+        if (setCookies == null) {
+            Main.warn("No 'Set-Cookie' in response header!");
             return null;
+        }
 
         for (String setCookie: setCookies) {
@@ -227,4 +229,5 @@
             }
         }
+        Main.warn("No suitable 'Set-Cookie' in response header found! {0}", setCookies);
         return null;
     }