Please provide more information like

Virsh version

Virsh dumpxml my-vm

qemu-info /foo/my-vm-snapshot.img

According to http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit your active block commit command should look like:

virsh blockcommit vm1 vda --active --verbose –pivot

thus one command…

Does your error comes after your third command?

Van: libvirt-users-bounces@redhat.com [mailto:libvirt-users-bounces@redhat.com] Namens Firat KÜÇÜK
Verzonden: zondag 13 december 2015 20:00
Aan: libvirt-users@redhat.com
Onderwerp: [libvirt-users] block-commit fails

Hello,

one of my VM's blockcommit job always fails. How can I find the reason? Error message is not clear.

virsh snapshot-create-as --domain my-vm backup-snapshot \
    --diskspec vda,file=/foo/my-vm-snapshot.img \
    --disk-only --atomic --no-metadata
 
virsh blockcommit my-vm vda --active --verbose --wait --async
virsh blockjob my-vm vda --pivot

internal error: unable to execute QEMU command 'block-job-complete': The active block job for device 'drive-virtio-disk0' cannot be completed