Issue

• virt-v2v to convert an ova file to qcow2 in order to use with the KVM fails with error.

virt-v2v -i ova [File].ova -o libvirt -of qcow2 -os default

[   0.0] Opening the source -i ova [File].ova
[   4.0] Creating an overlay to protect the source from being modified
[   4.0] Opening the overlay
virt-v2v: error: libguestfs error: could not create appliance through libvirt.

Try running qemu directly without libvirt using this environment variable:
export LIBGUESTFS_BACKEND=direct

Original error from libvirt: Cannot access backing file 
'/var/tmp/ova.YsvTyO/[File]-disk1.vmdk' of storage file 
'/var/tmp/v2vovl59c120.qcow2' (as uid:107, gid:107): Permission denied 
[code=38 domain=18]

If reporting bugs, run virt-v2v with debugging enabled and include the complete output:

  virt-v2v -v -x [...]