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

I reinstalled the usb drivers and ensured that I was not using USB 3.0 port.

I then closed out eclipse and killed and restarted adb.

Was immediately prompted on phone to allow computer access. After accepting I restarted eclipse and now my Galaxy S3 shows up in device Device Manager.

Answer 2

My resolution was running adb devices from the command prompt, pathed to the adb application. For example C:\Android\platform-tools\adb devices . Running this command returned the following * daemon not running. starting it now on port 5037 * *daemon started successfully *

I then saw the device listed as unauthorized, unplugges the USB, plugged back in and was prompted for the RSA fingerprint.

Answer 3

I solved this problem without deleting any keys. Here's how:

1. My device was connected to my computer via USB
2. I made sure Eclipse and android device monitor weren't running.
3. Typed at the commandline prompt: adb kill-server
4. Typed at the commandline prompt: adb start-server
5. After adb was restarted, I got a prompt on my device to authorize which I allowed.

Answer 4

Here is my version of the steps:

1. Make sure adb is running
2. In device go to Settings -> developer options -> Revoke USB debugging authorities
3. Disconnect device
4. In adb shell type > adb kill-server
5. In adb shell type > adb start-server
6. Connect device

if adb shell shows empty host name, restart device

Answer 5

I was facing same, issue, I found I was using a simple usb cable which was meant for only charge and not data copy. using good usb cable solved my problem !

Answer 6

Сhange USB connection mode from MTP to Camera (for Nexus 7) or, possibly, to Mass Storage or something else (for other devices). This option is usually under Settings -> Storage. Then connect the device again, you'll get the authorization dialog.

MTP has been known to interfere with USB debugging -- these two did not work together at all on majority of older devices. Nexus 7 and many newer devices do allow both to work alongside, but this particular issue suggests it's not all that smooth yet.

Bonus -- checklist for when adb is not behaving well:

• adb kill-server followed by adb start-server
• (on device) Settings -> Developer Options -> USB Debugging -- switch off and on
• [Windows] Make sure you have the proper driver (your best bet is Universal Adb Driver by Koushik Dutta -- will handle any device)
• [Windows] Try turning off all fancy on-the-fly anti-malware scanners/firewalls
• [Linux] Make sure you have the proper UDEV rule in /etc/udev/rules.d/51-android.rules (again, universal solution: https://github.com/snowdream/51-android)
• [Linux] Make sure everything under ~/.android is owned by you, not root (and upvote this answer)
• restart device (yes, surprisingly, this is a valid measure, too)
• (Obviously) replug cable, try different cable, different port, remove any extender cables