diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index 0e10de8..a69ca99 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -3449,6 +3449,10 @@
             final NetworkCallback callback;
             synchronized (sCallbacks) {
                 callback = sCallbacks.get(request);
+                if (message.what == CALLBACK_UNAVAIL) {
+                    sCallbacks.remove(request);
+                    callback.networkRequest = ALREADY_UNREGISTERED;
+                }
             }
             if (DBG) {
                 Log.d(TAG, getCallbackName(message.what) + " for network " + network);
@@ -3995,8 +3999,10 @@
         synchronized (sCallbacks) {
             Preconditions.checkArgument(networkCallback.networkRequest != null,
                     "NetworkCallback was not registered");
-            Preconditions.checkArgument(networkCallback.networkRequest != ALREADY_UNREGISTERED,
-                    "NetworkCallback was already unregistered");
+            if (networkCallback.networkRequest == ALREADY_UNREGISTERED) {
+                Log.d(TAG, "NetworkCallback was already unregistered");
+                return;
+            }
             for (Map.Entry<NetworkRequest, NetworkCallback> e : sCallbacks.entrySet()) {
                 if (e.getValue() == networkCallback) {
                     reqs.add(e.getKey());
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 37af461..3c5bb6a 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -3854,6 +3854,9 @@
         networkCallback.expectCallback(CallbackState.UNAVAILABLE, null);
         testFactory.waitForRequests();
 
+        // unregister network callback - a no-op, but should not fail
+        mCm.unregisterNetworkCallback(networkCallback);
+
         testFactory.unregister();
         handlerThread.quit();
     }