After updating to Android Studio 2 when I try to run my application and choose an emulator, I wait for the emulator to start and it suddenly gets killed. I can see emulator
In android studio version 4.0 (WINDOWS), I could find the solution by just checking android studio welcome screen and clicking on the "Events" dropdown AFTER trying to launch the emulator (hence after getting the error):
the events section clearly shows that ANDROID_SDK_ROOT was not set in my system.
In a nutshell, whenever you see such error when starting the emulator, just check the "events" section in the welcome to android studio screen to find the real problem.
Beware that if ANDROID_HOME is not set properly, it will still tell you that ANDROID_SDK_ROOT is broken.