How to solve ADB device unauthorized in Android ADB host device?

Question

When I\'m using a rooted Android device as ADB host to send adb command \"adb devices\" to Samsung S4, I received device unauthorized error message. However when I tried adb

Answer 1

You need to allow Allow USB debugging when the popup shows up when you first connect to the computer!

Answer 2

For me, the emulator could not have Google Play Services enabled. It could have Google APIs or be x86 or x64 but not google play store.

Answer 3

I had to check the box for the debugger on the phone "always allow on this phone". I then did a adb devices and then entered the adb command to clear the adds. It worked fine. Before that, it did not recognize the pm and other commands

Answer 4

If anyone has similar issue of having a phone with a cracked screen and has a need to access adb:

1. Root your phone (mine was already rooted, so I was blessed at least with that).

If you forgot to enable developers mode and your adb isn't running, then do the following:

1. Reboot your phone into recovery.
2. Connect the phone with a cable.
3. Open terminal.
4. If you type adb devices you should see the device in the list.

5. If so, type:

   adb shell mount /system
   abd shell
   
   echo "persist.service.adb.enable=1" >> default.prop 
   echo "persist.service.debuggable=1" >> default.prop
   echo "persist.sys.usb.config=mtp,adb" >> default.prop
   echo "persist.service.adb.enable=1" >> /system/build.prop 
   echo "persist.service.debuggable=1" >> /system/build.prop
   echo "persist.sys.usb.config=mtp,adb" >> /system/build.prop
   

Now if you are going to reboot into your phone android will tell you "oh your adb is working but please tap on this OK button, so we can trust your PC". And obviously if we can't tap on the phone stay in the recovery mode and do the following (assuming you are not in the adb shell mode, if so first type exit):

cd ~/.android
adb push adbkey.pub /data/misc/adb/adb_keys

6. Hurray, it all should be hunky-dory now! Just reboot the phone and you should be able to access adb when the phone is running:

   adb shell reboot

P.S. Was using OS X and Moto X Style that's with the cracked screen.

Answer 5

For unknown reasons, I only had ~/.android/adbkey, but not ~/.android/adbkey.pub.

I guess that adb was unable to push the public key to the device, and thus the device could never show the authorization dialog.

After killing the adb server, removing the adbkey file and starting adb again, the authorization dialog popped up on the phone.

Answer 6

I found one solution with Nexus 5, and TWRP installed. Basically format was the only solution I found and I tried all solutions listed here before: ADB Android Device Unauthorized

Ask Google to make backup of your apps. Save all important files you may have on your phone

Please note that I decline all liability in case of failure as what I did was quite risky but worked in my case:

Enable USB debugging in developer option (not sure if it helped as device was unauthorized but still...)

Make sure your phone is connected to computer and you can access storage

Download google img of your nexus: https://developers.google.com/android/nexus/images unrar your files and places them in a new folder on your computer, name it factory (any name will do).

wipe ALL datas... you will have 0 file in your android accessed from computer.

Then reboot into BOOTLOADER mode... you will have the message "you have no OS installed are you sure you want to reboot ?"

Then execute (double click) the .bat file inside the "factory" folder.

You will see command line detailed installation of the OS. Of course avoid disconnecting cable during this phase...

Phone will take about 5mn to initialize.