Five days ago I installed Android Studio on a fully updated Ubuntu 2018.04, used the wizard to create an example app, pressed the "Run" button and it ran perfectly on my Android device connected via USB.
Today, on the same Ubuntu and with the same deviced plugged in, I opened the same project and pressed "Run" again. It now fails:
Launching Application $ adb push /home/nico/src/ActionBarCompat-Basic/Application/build/outputs/apk/debug/Application-debug.apk /data/local/tmp/com.example.android.actionbarcompat.basic com.android.ddmlib.AdbCommandRejectedException: insufficient permissions for device: user in plugdev group; are your udev rules wrong? See [http://developer.android.com/tools/device.html] for more information Error while Installing APK
I did not knowingly modify any Ubuntu configuration or even update the OS.
What could be the problem?
How to investigate further?