diff --git a/mozilla/netwerk/base/src/nsStreamListenerProxy.cpp b/mozilla/netwerk/base/src/nsStreamListenerProxy.cpp
index e5b47efaa52..40dffd17d80 100644
--- a/mozilla/netwerk/base/src/nsStreamListenerProxy.cpp
+++ b/mozilla/netwerk/base/src/nsStreamListenerProxy.cpp
@@ -176,6 +176,12 @@ nsOnDataAvailableEvent::HandleEvent()
             rv = NS_ERROR_NOT_IMPLEMENTED;
         }
 
+        // Cancel the request on unexpected errors
+        if (NS_FAILED(rv) && (rv != NS_BASE_STREAM_CLOSED)) {
+            LOG(("OnDataAvailable failed [rv=%x] canceling request!\n"));
+            mRequest->Cancel(rv);
+        }
+
         //
         // Update the listener status
         //
diff --git a/mozilla/netwerk/base/src/nsStreamObserverProxy.cpp b/mozilla/netwerk/base/src/nsStreamObserverProxy.cpp
index 681984774af..c7017a8a2c8 100644
--- a/mozilla/netwerk/base/src/nsStreamObserverProxy.cpp
+++ b/mozilla/netwerk/base/src/nsStreamObserverProxy.cpp
@@ -122,7 +122,12 @@ nsOnStartRequestEvent::HandleEvent()
         return NS_ERROR_FAILURE;
     }
 
-    return observer->OnStartRequest(mRequest, mContext);
+    nsresult rv = observer->OnStartRequest(mRequest, mContext);
+    if (NS_FAILED(rv)) {
+        LOG(("OnStartRequest failed [rv=%x] canceling request!\n", rv));
+        mRequest->Cancel(rv);
+    }
+    return rv;
 }
 
 //