I'm following the directions here and in the related question here.
I have run the following in my guest Ubuntu os:
$ sudo apt install build-essential module-assistant dkms
$ sudo m-a prepare
But the next direction, "In VirtualBox menu bar, select Devices > Insert Guest Additions CD image." fails and gives me a popup with the message,
In VirtualBox menu bar, select Devices > Insert Guest Additions CD image.
How do I fix this?
