i\'m using android studio 2.1.1 in ubuntu 14.04.Now my question is,i want to run the program through my phone without emulator. so i chose the target as usb dev
I had this problem after upgrading from Android Studio 2.3 to 3.0. As simple as it sounds, I actually just restarted my phone to fix it.
My guess is that the adb server on the phone somehow cached something from the previous installation of android studio, maybe a connection object or something, and by restarting the adb server it resolved the issue.
I hope this helps someone.