failed to authenticate to <ip> | adb wifi

Question

When connecting a device with ADB Wireless, got failed to authenticate to <ip>

adb devices gives the device shows up as unauthorized.

Answer 1

From Android 4.2, every ADB device needs to be authorized for a computer to connect. This is done for security. So when a USB is connected a prompt comes asking to authorize the device when USB debugging is set. But does not happen for WIFI ADB.

So the workaround is to connect the device by USB, accepting the machine always. Then when the Wireless ADB is tried, it should work.

Answer 2

Solution

1 Connect device(over USB) to computer (WINDOWS).

2 Authorize adb device, so it can communicate(handshake over USB) with computer

3 Check that the device is connected

$adb devices  List of devices attached  SC8SDQWGKBT4JVS4        device 

4 Change to tcpip mode

$adb tcpip 5555  restarting in TCP mode port: 5555 

5 Connect device(over WIFI) to computer, make sure both are on the same network

$adb connect 192.168.1.100  connected to 192.168.1.100:5555 

6 Authorize adb device, so it can communicate(handshake over WIFI) with computer

7 Check that the device is connected

$adb devices  List of devices attached  SC8SDQWGKBT4JVS4        device  192.168.1.100:5555      unauthorized 

Although I authorized the device, adb is seeing things differently.

To get things working correctly, unplug device from USB because there is a connection over WIFI.

8 Kill the adb server

$adb kill-server 

9 Connect again over WIFI

$adb connect 192.168.1.100  * daemon not running. starting it now on port 5037 *  * daemon started successfully *  connected to 192.168.1.100:5555 

10 Finally, Check that the device is connect

$adb devices  List of devices attached  192.168.1.100:5555      device 

Device is now authorized, you can start debugging over WIFI.