Can't connect Nexus 4 to adb: unauthorized

Question

I have a Nexus 4 with Android 4.3 and I am trying to connect the device to a computer with Windows 7 64bit.

I installed the latest drivers and the latest adb

Answer 1

Four easy steps

./adb kill-server ./adb start-server

replug the device, unlock it and accept the new key

Answer 2

When I turn off my Comodo Antivirus everything goes back normal. All other solutions suggested here went in vain. Somehow I figured out one solution.

If you are using Comodo Antivirus (Version 6.3/ For other versions search for similar options) the following solution would help you.

Open Comodo > Tasks > Advanced Tasks > Open Advanced Settings > Security Settings > Firewall > Firewall Settings > Advanced : Filter loopback traffic (e.g. 127.x.x.x, ::1)

Uncheck this "Filter loopback traffic" option, which prevents adb from normal working.

Answer 3

I was not getting the RSA fingerprint pop up on my phone.

I had to delete the C:\Users\<userName>\.android\adbkey and adbkey.pub files and then do kill and restart of adb server.

adb kill-server
adb start-server

I had to stop and restart the debugger and connecting as USB in PTP mode.

Because the RSA authorisation key was getting stored in this path, killing and restarting the adb server didn't help.

Answer 4

For my Samsung S3, I had to go into Developer Options on the phone, untick the "USB debugging" checkbox, then re-tick it.

Then the dialog will appear, asking if you want to allow USB Debugging.

Once I'd done this, the "adb devices" command no longer showed "unauthorized" as my device name.

(Several months later..)

Actually, the same was true for connecting my Galaxy Tab S device, and the menu options were in slightly different places with Android 4.4.2:

Answer 5

1.) Delete ~/.android/adbkey on your desktop machine

2.) Run command "adb kill-server"

3.) Run command "adb start-server"

You should now be prompted to accept debug key.

Answer 6

I had to re-install my adb driver to snap out of this probelm. I had install "Universal Naked Driver" in an effort to recover my phone. I uninstalled that and re-installed the driver out of the android sdk.