We had also the same issue with a vm after install the host complety new. We changed from ubuntu 12.04 to Proxmox 3.3.
Unfortunately the qemu-img version compiled on Trusty Thar don't work under Proxmox 3.3 so i compiled it under Proxmox :) For all people the run into the same issue he ist the file. ** Attachment added: "qemu-img version 1.7.2 compiled on Proxmox 3.3" https://bugs.launchpad.net/qemu/+bug/1354167/+attachment/4269614/+files/qemu-img -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1354167 Title: On VM restart: Could not open 'poppy.qcow2': Could not read snapshots: File too large Status in QEMU: New Bug description: I'm unable to restart a VM. virt-manager is giving me: Error starting domain: internal error: process exited while connecting to monitor: qemu-system-x86_64: -drive file=/var/lib/libvirt/images/poppy.qcow2,if=none,id=drive-virtio- disk0,format=qcow2: could not open disk image /var/lib/libvirt/images/poppy.qcow2: Could not read snapshots: File too large From the command line trying to check the image also gives me: qemu-img check poppy.qcow2 qemu-img: Could not open 'poppy.qcow2': Could not read snapshots: File too large This bug appears with both the default install of qemu for ubuntu 14.04: qemu-img version 2.0.0, Copyright (c) 2004-2008 Fabrice Bellard And the latest version. qemu-img version 2.1.50, Copyright (c) 2004-2008 Fabrice Bellard Host: Dual E5-2650 v2 @ 2.60GHz 32GB Memory 4TB Disk space (2.1TB Free) Host OS: Ubuntu 14.04.1 LTS 64bit Guest: Ubuntu 14.04 64bit Storage Size: 500gb To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1354167/+subscriptions