Problem with ADB on my Nexus 4 (unauthorized phone)

Question

When running adb devices in cmd, it says that my phone is unauthorized. It appears that it has something to do with the RSA fingerprint prompt. I don't remember ever getting such a prompt. Yes, I am running in PTP mode and debugging is enabled. I tried, after looking around on internet for multiple hours:

• Enabling/disabling debugging mode repeatedly
• Uninstalling and reinstalling my drivers for my phone or ADB
• adb-killserver and adb-startserver
• Restarting my phone and unplugging/replugging in multiple ways

I did notice that in my (user)/.android/ folder, I don't have a file called adbkey.pub (which is apparently the file that's supposed to have my key). Anyway, I don't think I've ever received the prompt about RSA fingerprint and I can't make it appear in any way.

Do you guys have any idea what I could do at this point. I tried about everything on these forums and around on the Internet but maybe there is something else I could do. Should I reset my phone to factory settings at this point to make the prompt appear again?

Answer 1

Couple of things could help:

• actually, sometimes happens that you cable, used for connection is getting broken, try with another one
• when connected, in notification shade select USB for charging and change it to either MTP or Storage

Answer 2

There are two possibilities:

1. Update your pre 4.2.x SDK to the latest version that includes RSA auth.

2. If I'm right to assume you're running Linux (user/.android/). In case of Ubuntu/Debian: The 'android-tools-adb' package provides the adb binary which is preferred to that of the SDK. If it is installed, it must be recent (>4.2), because RSA authentication isn't integrated in earlier versions. You can manually download that of Roaring and install it on 12.xx, i have tested this already and it worked. Or just use that from the SDK. Be sure to kill the old adb server instance after upgrading/fixing the version.