Why ADB says unauthorized
Android validates the controlling computer’s ADB public key against an approved key list. On a normal phone, an authorization dialog appears. Screenless boards cannot show the same dialog, so their setup depends on manufacturer provisioning or an authorized existing key.
Fix the connection in order
Check cable and USB mode, close applications that already own the ADB interface, ensure the browser supports WebUSB, and verify the device is recognized. For phones with screens, confirm debugging is enabled and authorize the computer on the phone.
Screenless boards and key imports
If the farm was previously managed on a trusted computer, an administrator may be able to import its own existing ADB key through the PhoneFarm key interface. Treat private ADB keys as sensitive credentials and obtain permission before transferring them. Never publish private keys or import unknown keys from untrusted downloads.
When the problem is not authorization
If the device does not appear in the USB picker at all, investigate operating-system USB access, cable quality, USB hub power, browser support and proprietary box protocol before focusing on keys.
Research notes reflect publicly documented product information checked October 16, 2026. Prices, features and compatibility may change. PhoneFarm is independent and is not affiliated with the vendors named on this page.