Android SDK 在 PC机上 运行adb shell 不成功（环境变量已经配好了）,该如何处理

Android SDK 在 PC机上 运行adb shell 不成功（环境变量已经配好了）
我输入adb可以成功
输入adb shell为什么提示：error: protocol fault (no status) 呢 ？

------解决方案--------------------
Code:
C:\AndroidSDK\tools>adb devices
error: protocol fault (no status)

after searching for 2 days through various posts I still could not get it to work, even though it had worked fine previously.In the end it was a simple fix

Open task manager and search for adb.exe and right click > end process.

Hope this helps someone else 

google搜到的，多用用百度，谷歌吧
------解决方案--------------------
adb会卡死是常例。适当重启adb服务，这类问题是常有的。