What is the correct way to install Ubuntu 16.04 as a guest OS?

Question

Virtualization

The server has Ubuntu 16.04.1 installed and the KVM hypervisor
1) Created a virtual machine with boot from ubuntu 16.04.1 iso image
2) When installing the guest OS, I get an error:

Unable to mount installation CD. It may not be inserted in the CD-ROM drive. Try again?

How can this be if the installation has already started and in fact the system has already booted from the installation image?

Answer 1

I encountered such a problem not only when installing on a virtual machine, but also on ordinary hosts.
The solution is lying around on askubuntu, quote:

1. When you get the error, Alt+F2 to a second console.
   
2. Find out which device your USB stick is (tail -n 100 /var/log/syslog)
   
3. If the device is busy, umount it (umount /dev/sd[abcdef]1)
   
4. Then mount it to /cdrom (mount -t vfat /dev/sd[abcdef]1 /cdrom)
   
5. Alt+F1 to get back to the install console, and try detecting again