diff --git a/tests/net/java/com/android/server/connectivity/VpnTest.java b/tests/net/java/com/android/server/connectivity/VpnTest.java
index 32c6a75..9373da3 100644
--- a/tests/net/java/com/android/server/connectivity/VpnTest.java
+++ b/tests/net/java/com/android/server/connectivity/VpnTest.java
@@ -21,6 +21,8 @@
 import static android.content.pm.UserInfo.FLAG_PRIMARY;
 import static android.content.pm.UserInfo.FLAG_RESTRICTED;
 import static android.net.ConnectivityManager.NetworkCallback;
+import static android.net.INetd.IF_STATE_DOWN;
+import static android.net.INetd.IF_STATE_UP;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
@@ -61,6 +63,7 @@
 import android.net.INetd;
 import android.net.Ikev2VpnProfile;
 import android.net.InetAddresses;
+import android.net.InterfaceConfigurationParcel;
 import android.net.IpPrefix;
 import android.net.IpSecManager;
 import android.net.IpSecTunnelInterfaceResponse;
@@ -870,17 +873,28 @@
                         eq(AppOpsManager.MODE_IGNORED));
     }
 
-    private NetworkCallback triggerOnAvailableAndGetCallback() {
+    private NetworkCallback triggerOnAvailableAndGetCallback() throws Exception {
         final ArgumentCaptor<NetworkCallback> networkCallbackCaptor =
                 ArgumentCaptor.forClass(NetworkCallback.class);
         verify(mConnectivityManager, timeout(TEST_TIMEOUT_MS))
                 .requestNetwork(any(), networkCallbackCaptor.capture());
 
+        // onAvailable() will trigger onDefaultNetworkChanged(), so NetdUtils#setInterfaceUp will be
+        // invoked. Set the return value of INetd#interfaceGetCfg to prevent NullPointerException.
+        final InterfaceConfigurationParcel config = new InterfaceConfigurationParcel();
+        config.flags = new String[] {IF_STATE_DOWN};
+        when(mNetd.interfaceGetCfg(anyString())).thenReturn(config);
         final NetworkCallback cb = networkCallbackCaptor.getValue();
         cb.onAvailable(TEST_NETWORK);
         return cb;
     }
 
+    private void verifyInterfaceSetCfgWithFlags(String flag) throws Exception {
+        // Add a timeout for waiting for interfaceSetCfg to be called.
+        verify(mNetd, timeout(TEST_TIMEOUT_MS)).interfaceSetCfg(argThat(
+                config -> Arrays.asList(config.flags).contains(flag)));
+    }
+
     @Test
     public void testStartPlatformVpnAuthenticationFailed() throws Exception {
         final ArgumentCaptor<IkeSessionCallback> captor =
@@ -892,6 +906,8 @@
         final Vpn vpn = startLegacyVpn(createVpn(primaryUser.id), (mVpnProfile));
         final NetworkCallback cb = triggerOnAvailableAndGetCallback();
 
+        verifyInterfaceSetCfgWithFlags(IF_STATE_UP);
+
         // Wait for createIkeSession() to be called before proceeding in order to ensure consistent
         // state
         verify(mIkev2SessionCreator, timeout(TEST_TIMEOUT_MS))
@@ -910,6 +926,8 @@
         final Vpn vpn = startLegacyVpn(createVpn(primaryUser.id), mVpnProfile);
         final NetworkCallback cb = triggerOnAvailableAndGetCallback();
 
+        verifyInterfaceSetCfgWithFlags(IF_STATE_UP);
+
         // Wait for createIkeSession() to be called before proceeding in order to ensure consistent
         // state
         verify(mConnectivityManager, timeout(TEST_TIMEOUT_MS)).unregisterNetworkCallback(eq(cb));