代码:
1. 修改/etc/dbus-1/system.d/NetworkManager.conf 和 /etc/dbus-1/system.d/nm-applet.conf
將下列红色字，如果为deny，改allow
<policy context=default>
<allow own="org.freedesktop.NetworkManager"/>
<allow send_destination="org.freedesktop.NetworkManager"/>
<allow send_interface="org.freedesktop.NetworkManager"/>
</policy>

2. 重新启动 dbus
sudo /etc/init.d/dbus restart

* Fix nm-applet "No connection defined" error

3. 停止 NetworkManager
sudo /etc/init.d/network-manager stop

4. 刪除 /etc/network/interfaces 或是更名(rename)
sudo rm /etc/network/interfaces

5. 重新启动 NetworkManager
sudo /etc/init.d/network-manager start