diff --git a/backend/SystemUpdater/UpdateManagerDbus.py b/backend/SystemUpdater/UpdateManagerDbus.py
index cb58bd0..cfe3ee1 100755
--- a/backend/SystemUpdater/UpdateManagerDbus.py
+++ b/backend/SystemUpdater/UpdateManagerDbus.py
@@ -120,11 +120,11 @@ class UpdateManagerDbusController(dbus.service.Object):
             obj = self.bus.get_object("org.freedesktop.NetworkManager","/org/freedesktop/NetworkManager")
             interface = dbus.Interface(obj, "org.freedesktop.NetworkManager")
             retval = interface.CheckConnectivity(timeout=0.5)
-            #1 表示没有网卡可以使用
-            if retval == 1:
-                raise UpdateBaseError(enums.ERROR_NETWORK_FAILED)
         except Exception:
-            pass
+            retval = 4
+        #1 表示没有网卡可以使用
+        if retval == 1:
+            raise UpdateBaseError(enums.ERROR_NETWORK_FAILED)
 
     def _check_prohibit_user(self, sender_name):
         prohibit_list = ["dbus-send","gdbus"]