[libvirt-users] Using qemu active blockcommit results in 'Permission denied' error

Hello all, I tried following this guide: https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit Unfortunately when I try to do the final virsh blockcommit step I always get the following error: error: internal error: unable to execute QEMU command 'block-commit': Could not reopen file: Permission denied I checked directory und image file permissions, app-armor profiles (set to complain mode for now.) and libvirt logs but nothing there gives me any hints what might be going wrong. This is on a debian buster system, using libvirtd (libvirt) 5.0.0 qemu 3.1+dfsg-7 I would appreciate any hints on how to proceed/get more debug info on this. Thanks! Marcus