virtualbox.org

I moved a vm from one drive to another on my host machine. I then went to preferences to change my default machine folder and I noticed a 'invalid setting detected' message that says "Host interface VirtualBox Host only ethernet adapter does not currently have a valid IPv4 network mask. I put in the IPv4 address and subnet mask from my host machine, but vb does not like that one. What ip address and subnet mask should I use?
Thanks!

I am confused by this. Why would you change something in the vm when the message is complaining about the interface in the host?

You do not need to manually configure the NIC in the guest if it is using host only. It is automatically configured from the host by DHCP.

What config does the host only interface on the host machine have? It should be 192.168.56.1 with a 32-bit subnet mask (255.255.255.0).