no permissions (user in plugdev group; are your udev rules wrong?)

I was trying to use adb on my connected phone, but somehow adb devices showed me this

$ adb devices
List of devices attached
7e0d288f no permissions (user in plugdev group; are your udev rules wrong?); see [http://developer.android.com/tools/device.html]

Solution

Before you try any complex solutions out there, try change your phone mode to File Transfer or MTP.

Yes! Simply set the phone to File transfer or MTP (whichever exists) and the issue is fixed.

Don’t forget to allow USB debugging access prompt that might pop up on your phone screen after that.