TeraByte Unlimited

I have learned the process to restore a TBI to a bootable VM using TBOSDT and copyp2v.tbs. (Video in copyp2v-vista.wmv)

I tried the same script with an image of a Linux machine created with IFL. copyp2v.tbs reports "Unable to access Windows installation". So I assume it is a windows-only script.

I used IFW to restore to a VMDK file. In the restore, I select Set Active, Update Boot Partition, Write standard MBR.
Then I created a new VM and selected the VMDK as the disk.
This results in the Missing Operating system message and fails to boot.
The original drive had 3 NTFS partitions left over from a prior Windows install, and one Linux ext partition. I did not restore any of the NTFS partitions into the VMDK.

Are there any guidelines for solving boot issues in a Linux VM in Virtualbox?

I don't know if this is the best solution, but here's how I solved it.
I added the original Linux ISO as a CDROM on the VM. bionicpup32-8.0-uefi.iso
I booted into the Live CD mode of the CDROM.
From there, I was able to run Grub4DOS Bootloader Config.
It recognized the VM drive as SDA1 and made it bootable.
Then I removed the CDROM, and restarted the VM, and it booted correctly into the Linux environment.

yes the script is for Windows, Linux you don't need to do anything much, you'd just copy the drive or backup/restore it. If you do entire drive your good, if you do individual partitions, you have to restore the boot partition first and use set the active partition, then restore os with update boot partition. You can use the restore first track option as well, set number of sectors to 0 to restore all. The message you got is typically if there is no active boot partition (or old boot code using chs and the geometry is different than expected).