adb: device "unauthorized"

Error text

adb devices
List of devices attached
R58M123ABC    unauthorized

Cause

The phone has not granted USB debugging permission to this computer. A confirmation dialog should appear on its screen.

Step-by-step fix

1. Unlock the phone and keep the screen on; look for the confirmation dialog.
2. Choose "Always allow from this computer" and tap Allow.
3. If no dialog appears, use Revoke USB debugging authorizations in Developer options.
4. Replug the cable and run adb kill-server and adb start-server.
5. Make sure the cable carries data, not only charge.

Example commands

adb kill-server
adb start-server
adb devices
# telefonda: Developer options > Revoke USB debugging authorizations

How to prevent it

Keep a quality data cable for the test phone.

Author and license: Nibras Code