diff --git a/framework/src/android/net/NetworkCapabilities.java b/framework/src/android/net/NetworkCapabilities.java
index ed9df56..ec71d3d 100644
--- a/framework/src/android/net/NetworkCapabilities.java
+++ b/framework/src/android/net/NetworkCapabilities.java
@@ -1585,6 +1585,28 @@
     }
 
     /**
+     * Compare if the given NetworkCapabilities have the same UIDs.
+     *
+     * @hide
+     */
+    public static boolean hasSameUids(@Nullable NetworkCapabilities nc1,
+            @Nullable NetworkCapabilities nc2) {
+        final Set<UidRange> uids1 = (nc1 == null) ? null : nc1.mUids;
+        final Set<UidRange> uids2 = (nc2 == null) ? null : nc2.mUids;
+        if (null == uids1) return null == uids2;
+        if (null == uids2) return false;
+        // Make a copy so it can be mutated to check that all ranges in uids2 also are in uids.
+        final Set<UidRange> uids = new ArraySet<>(uids2);
+        for (UidRange range : uids1) {
+            if (!uids.contains(range)) {
+                return false;
+            }
+            uids.remove(range);
+        }
+        return uids.isEmpty();
+    }
+
+    /**
      * Tests if the set of UIDs that this network applies to is the same as the passed network.
      * <p>
      * This test only checks whether equal range objects are in both sets. It will
@@ -1600,19 +1622,7 @@
      */
     @VisibleForTesting
     public boolean equalsUids(@NonNull NetworkCapabilities nc) {
-        Set<UidRange> comparedUids = nc.mUids;
-        if (null == comparedUids) return null == mUids;
-        if (null == mUids) return false;
-        // Make a copy so it can be mutated to check that all ranges in mUids
-        // also are in uids.
-        final Set<UidRange> uids = new ArraySet<>(mUids);
-        for (UidRange range : comparedUids) {
-            if (!uids.contains(range)) {
-                return false;
-            }
-            uids.remove(range);
-        }
-        return uids.isEmpty();
+        return hasSameUids(nc, this);
     }
 
     /**
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 48ae7a0..899286b 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -7348,6 +7348,8 @@
             mDnsManager.updateTransportsForNetwork(
                     nai.network.getNetId(), newNc.getTransportTypes());
         }
+
+        maybeSendProxyBroadcast(nai, prevNc, newNc);
     }
 
     /** Convenience method to update the capabilities for a given network. */
@@ -7440,6 +7442,30 @@
         maybeCloseSockets(nai, ranges, exemptUids);
     }
 
+    private boolean isProxySetOnAnyDefaultNetwork() {
+        ensureRunningOnConnectivityServiceThread();
+        for (final NetworkRequestInfo nri : mDefaultNetworkRequests) {
+            final NetworkAgentInfo nai = nri.getSatisfier();
+            if (nai != null && nai.linkProperties.getHttpProxy() != null) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private void maybeSendProxyBroadcast(NetworkAgentInfo nai, NetworkCapabilities prevNc,
+            NetworkCapabilities newNc) {
+        // When the apps moved from/to a VPN, a proxy broadcast is needed to inform the apps that
+        // the proxy might be changed since the default network satisfied by the apps might also
+        // changed.
+        // TODO: Try to track the default network that apps use and only send a proxy broadcast when
+        //  that happens to prevent false alarms.
+        if (nai.isVPN() && nai.everConnected && !NetworkCapabilities.hasSameUids(prevNc, newNc)
+                && (nai.linkProperties.getHttpProxy() != null || isProxySetOnAnyDefaultNetwork())) {
+            mProxyTracker.sendProxyBroadcast();
+        }
+    }
+
     private void updateUids(NetworkAgentInfo nai, NetworkCapabilities prevNc,
             NetworkCapabilities newNc) {
         Set<UidRange> prevRanges = null == prevNc ? null : prevNc.getUidRanges();
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index 4530650..be7239d 100644
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -486,6 +486,7 @@
     @Mock VpnProfileStore mVpnProfileStore;
     @Mock SystemConfigManager mSystemConfigManager;
     @Mock Resources mResources;
+    @Mock ProxyTracker mProxyTracker;
 
     private ArgumentCaptor<ResolverParamsParcel> mResolverParamsParcelCaptor =
             ArgumentCaptor.forClass(ResolverParamsParcel.class);
@@ -1280,10 +1281,14 @@
             return mMockNetworkAgent;
         }
 
-        public void establish(LinkProperties lp, int uid, Set<UidRange> ranges, boolean validated,
-                boolean hasInternet, boolean isStrictMode) throws Exception {
+        private void setOwnerAndAdminUid(int uid) throws Exception {
             mNetworkCapabilities.setOwnerUid(uid);
             mNetworkCapabilities.setAdministratorUids(new int[]{uid});
+        }
+
+        public void establish(LinkProperties lp, int uid, Set<UidRange> ranges, boolean validated,
+                boolean hasInternet, boolean isStrictMode) throws Exception {
+            setOwnerAndAdminUid(uid);
             registerAgent(false, ranges, lp);
             connect(validated, hasInternet, isStrictMode);
             waitForIdle();
@@ -1638,7 +1643,7 @@
         doReturn(mNetIdManager).when(deps).makeNetIdManager();
         doReturn(mNetworkStack).when(deps).getNetworkStack();
         doReturn(mSystemProperties).when(deps).getSystemProperties();
-        doReturn(mock(ProxyTracker.class)).when(deps).makeProxyTracker(any(), any());
+        doReturn(mProxyTracker).when(deps).makeProxyTracker(any(), any());
         doReturn(true).when(deps).queryUserAccess(anyInt(), any(), any());
         doAnswer(inv -> {
             mPolicyTracker = new WrappedMultinetworkPolicyTracker(
@@ -10382,16 +10387,23 @@
 
     @Test
     public void testVpnUidRangesUpdate() throws Exception {
-        LinkProperties lp = new LinkProperties();
+        // Set up a WiFi network without proxy.
+        mWiFiNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_WIFI);
+        mWiFiNetworkAgent.connect(true);
+        assertNull(mService.getProxyForNetwork(null));
+        assertNull(mCm.getDefaultProxy());
+
+        final LinkProperties lp = new LinkProperties();
         lp.setInterfaceName("tun0");
         lp.addRoute(new RouteInfo(new IpPrefix(Inet4Address.ANY, 0), null));
         lp.addRoute(new RouteInfo(new IpPrefix(Inet6Address.ANY, 0), null));
         final UidRange vpnRange = PRIMARY_UIDRANGE;
-        Set<UidRange> vpnRanges = Collections.singleton(vpnRange);
+        final Set<UidRange> vpnRanges = Collections.singleton(vpnRange);
         mMockVpn.establish(lp, VPN_UID, vpnRanges);
         assertVpnUidRangesUpdated(true, vpnRanges, VPN_UID);
+        // VPN is connected but proxy is not set, so there is no need to send proxy broadcast.
+        verify(mProxyTracker, never()).sendProxyBroadcast();
 
-        reset(mMockNetd);
         // Update to new range which is old range minus APP1, i.e. only APP2
         final Set<UidRange> newRanges = new HashSet<>(Arrays.asList(
                 new UidRange(vpnRange.start, APP1_UID - 1),
@@ -10401,6 +10413,101 @@
 
         assertVpnUidRangesUpdated(true, newRanges, VPN_UID);
         assertVpnUidRangesUpdated(false, vpnRanges, VPN_UID);
+
+        // Uid has changed but proxy is not set, so there is no need to send proxy broadcast.
+        verify(mProxyTracker, never()).sendProxyBroadcast();
+
+        final ProxyInfo testProxyInfo = ProxyInfo.buildDirectProxy("test", 8888);
+        lp.setHttpProxy(testProxyInfo);
+        mMockVpn.sendLinkProperties(lp);
+        waitForIdle();
+        // Proxy is set, so send a proxy broadcast.
+        verify(mProxyTracker, times(1)).sendProxyBroadcast();
+        reset(mProxyTracker);
+
+        mMockVpn.setUids(vpnRanges);
+        waitForIdle();
+        // Uid has changed and proxy is already set, so send a proxy broadcast.
+        verify(mProxyTracker, times(1)).sendProxyBroadcast();
+        reset(mProxyTracker);
+
+        // Proxy is removed, send a proxy broadcast.
+        lp.setHttpProxy(null);
+        mMockVpn.sendLinkProperties(lp);
+        waitForIdle();
+        verify(mProxyTracker, times(1)).sendProxyBroadcast();
+        reset(mProxyTracker);
+
+        // Proxy is added in WiFi(default network), setDefaultProxy will be called.
+        final LinkProperties wifiLp = mCm.getLinkProperties(mWiFiNetworkAgent.getNetwork());
+        assertNotNull(wifiLp);
+        wifiLp.setHttpProxy(testProxyInfo);
+        mWiFiNetworkAgent.sendLinkProperties(wifiLp);
+        waitForIdle();
+        verify(mProxyTracker, times(1)).setDefaultProxy(eq(testProxyInfo));
+        reset(mProxyTracker);
+    }
+
+    @Test
+    public void testProxyBroadcastWillBeSentWhenVpnHasProxyAndConnects() throws Exception {
+        // Set up a WiFi network without proxy.
+        mWiFiNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_WIFI);
+        mWiFiNetworkAgent.connect(true);
+        assertNull(mService.getProxyForNetwork(null));
+        assertNull(mCm.getDefaultProxy());
+
+        final LinkProperties lp = new LinkProperties();
+        lp.setInterfaceName("tun0");
+        lp.addRoute(new RouteInfo(new IpPrefix(Inet4Address.ANY, 0), null));
+        lp.addRoute(new RouteInfo(new IpPrefix(Inet6Address.ANY, 0), null));
+        final ProxyInfo testProxyInfo = ProxyInfo.buildDirectProxy("test", 8888);
+        lp.setHttpProxy(testProxyInfo);
+        final UidRange vpnRange = PRIMARY_UIDRANGE;
+        final Set<UidRange> vpnRanges = Collections.singleton(vpnRange);
+        mMockVpn.setOwnerAndAdminUid(VPN_UID);
+        mMockVpn.registerAgent(false, vpnRanges, lp);
+        // In any case, the proxy broadcast won't be sent before VPN goes into CONNECTED state.
+        // Otherwise, the app that calls ConnectivityManager#getDefaultProxy() when it receives the
+        // proxy broadcast will get null.
+        verify(mProxyTracker, never()).sendProxyBroadcast();
+        mMockVpn.connect(true /* validated */, true /* hasInternet */, false /* isStrictMode */);
+        waitForIdle();
+        assertVpnUidRangesUpdated(true, vpnRanges, VPN_UID);
+        // Vpn is connected with proxy, so the proxy broadcast will be sent to inform the apps to
+        // update their proxy data.
+        verify(mProxyTracker, times(1)).sendProxyBroadcast();
+    }
+
+    @Test
+    public void testProxyBroadcastWillBeSentWhenTheProxyOfNonDefaultNetworkHasChanged()
+            throws Exception {
+        // Set up a CELLULAR network without proxy.
+        mCellNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_CELLULAR);
+        mCellNetworkAgent.connect(true);
+        assertNull(mService.getProxyForNetwork(null));
+        assertNull(mCm.getDefaultProxy());
+        // CELLULAR network should be the default network.
+        assertEquals(mCellNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+
+        // Set up a WiFi network without proxy.
+        mWiFiNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_WIFI);
+        mWiFiNetworkAgent.connect(true);
+        assertNull(mService.getProxyForNetwork(null));
+        assertNull(mCm.getDefaultProxy());
+        // WiFi network should be the default network.
+        assertEquals(mWiFiNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+        // CELLULAR network is not the default network.
+        assertNotEquals(mCellNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+
+        // CELLULAR network is not the system default network, but it might be a per-app default
+        // network. The proxy broadcast should be sent once its proxy has changed.
+        final LinkProperties cellularLp = new LinkProperties();
+        cellularLp.setInterfaceName(MOBILE_IFNAME);
+        final ProxyInfo testProxyInfo = ProxyInfo.buildDirectProxy("test", 8888);
+        cellularLp.setHttpProxy(testProxyInfo);
+        mCellNetworkAgent.sendLinkProperties(cellularLp);
+        waitForIdle();
+        verify(mProxyTracker, times(1)).sendProxyBroadcast();
     }
 
     @Test