Android Debug Bridge (adb) is a command line tools that lets you communicate with an emulator instance or connected Android-powered device. Read details here
Resetting ADB is a common fix to errors related to Android emulator or Android-powered device used while developing Android application.
This is how to reset ADB.
- Go to Window >> Show View >> Devices.
If Devices is not present under Show View, click Other submenu. This will open Show View dialog. Select Devices under Android.
- Under Devices window, click Reset adb (under it’s menu, arrow down besides minimize button)