Android Studio error: cannot connect to daemon

I had same problem a moment ago. I solved it:

Run CMD as Administrator

Enter adb devices to CMD.

The output for me is :

C:\WINDOWS\system32>adb devices
List of devices attached
* daemon not running; starting now at tcp:5037
* daemon started successfully
P9BCS87ABS9SCD5 device

The solution which worked for me -

Open Command Prompt as administrator and type

adb start-server

That's it