Apt configuration problem. An attempt to configure apt to install additional packages from the CD failed

I’ve installed new OpenNebula based server.
Debian 10.2 + Opennebula 5.10.1
then I’ve created 2 templates. Windows template works fine. But Debian template fails with error.

But during Debian installation there is this error.
I believe this is somehow related to virtual drive “context” that is mounted, and I cannot disable it.

debian_template.txt (1.1 KB)

I found it!
If I remove


installation goes successfully