adb server version doesn't match this client

Question

Whenever I try to run adb devices:

            $ adb devices
            * daemon not running. starting it now *
            * daemon started su         


        

Answer 1

First close All the things which use ADB. (Android Studio, Eclipse, Emulator(Bluestack as well)) and then do

adb kill-server
adb start-server

In my case I just got update of Studio.