[android] Android ADB devices unauthorized

In Android studio, Run menu > Run shows OFFLINE ... for the connected device.

Below is the procedure followed to solve it:

  1. (Read the below note first) Delete the ~/.android/adbkey (or, rename to ~/.android/adbkey2, this is even better incase you want it back for some reason)
    Note: I happened to do this step, but it didn't solve the problem, after doing all the below steps it worked, so unsure if this step is required.

  2. Run locate platform-tools/adb
    Note: use the path that comes from here in below commands

  3. Kill adb server:
    sudo ~/Android/Sdk/platform-tools/adb kill-server

  4. You will get a Allow accept.. message popup on your device. Accept it. This is important, which solves the problem.

  5. Start adb server:
    sudo ~/Android/Sdk/platform-tools/adb start-server

  6. In Android studio, do Run menu > Run again
    It will show something like Samsung ... (your phone manufacture name).
    Also installs the apk on device correctly this time without error.

Hope that helps.