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]
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.