[Libguestfs] Re: Can't boot UEFI VM after migration: "error: can't find command `linux16`"

On Fri, May 15, 2026 at 09:24:25AM -0000, sparimi--- via Libguestfs wrote: > Hi > > I am trying to solve this above issue. The problem happens when we > convert RHEL 7.9 VMware VM using virt-v2v to KVM (not limited to > RHEL 7.9). These are the steps > > 1. Create a RHEL7.9 VM in vmware Is this using UEFI or BIOS?

> 2. Boot the VM in VMware, and change the /etc/fstab to have > /dev/sda* instead of FS partition UUID where initramfs and vmlinuz > are to be found. I think an example could be worth a 1000 words here. What does the /etc/fstab file look like before & after this change? Are you adding new entries or changing existing ones?

> 3. Power down the VM > 4. Use virt-v2v to convert the VM - successfully done > 5. If we try to boot the converted VM, the error messages show up > error: can't find command linux16 > error: can't find command initrd16 > > While debugging the problem - I localized the source which in my understanding could be problematic > > In File virt-v2v/convert/convert_linux.ml > > Line Number ~1265 > if String.starts_with "/files/etc/crypttab" path && > String.starts_with "/dev/sd" value then ( > try > let uuid = g#vfs_uuid value in > "UUID=" ^ uuid > with ex -> > warning (f_"failed to translate encrypted device name %s to a UUID \ > in /etc/crypttab. This may prevent the guest from booting \ > after conversion. You may have to manually change the file and \ > reconvert. The original error was: %s") > value (Printexc.to_string ex); > adjusted_dev > ) else > adjusted_dev > This is from function remap_block_devices, while it checks for > /etc/crypttab and device file, and determines the UUID of the device > file, it does not seem to consider /etc/fstab entries for similar > exercise. This seems to be related to the problem at hand. We definitely do check /etc/fstab for device names and replace (eg.) /dev/sda with /dev/vda, but we don't replace filesystem device names with UUID=<uuid>s at the moment. This is a wishlist item. Whether it'll fix the current bug, I don't know. It's not clear to me why grub would care about the contents of /etc/fstab, but then grub is a big mystery for everyone!

Did you try modifying virt-v2v? What was the result?

Posting the full virt-v2v conversion log is usually helpful too.

Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html