no target device found android studio 2.1.1

Question

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

Answer 1

This happened to me on android studio version 4 after doing an update to the IDE. The "invalidate caches and restart" option fixed it.