After upgrading to the latest Ubuntu and Android Studio versions, you have to do a few simple things in order to use the Android Emulator.

When you try to start an emulator, you will be required to grant access of the current user to /dev/kvm.

You can do this task with the following steps:

  1. Check if you already have a permission:
    grep kvm /etc/group
    If you see this: kvm:x:105:[YOUR_USER], you have a permission.
  2. Add your user:
    sudo adduser [YOUR_USER] kvm
  3. And the last step - logout

That's it! Now you can use the emulator! :)