解决方案：
a.先把eclipse关闭.
b.在命令提示符中转到你的android SDK
的platform-tools下
c.键入adb kill-server
d.再输入 adb start-server
Android :The connection to adb is down, and a severe error has occured.,布布扣,bubuko.com
Android :The connection to adb is down, and a severe error has occured.
原文：http://www.cnblogs.com/qingfengshuimu/p/3598074.html