KVM troubleshooting¶
Part of the KVM overview. Common libvirt and QEMU errors and their fixes.
| Symptom | Cause and fix |
|---|---|
KVM: disabled by BIOS |
Enable virtualization in the firmware setup. |
error: Failed to start domain ... Cannot access storage file '.../x.iso' |
The VM references an ISO that is gone. Detach it: virsh change-media vm01 sda --eject --config (or remove the CD-ROM <source> with virsh edit). |
| Guest has no network | The guest and host must not share a MAC address. Compare virsh domiflist with ip link on the host; regenerate the guest MAC if they collide. |
error: internal error No <source> 'bridge' attribute specified with <interface type='bridge'/> |
Use <source bridge='br0'/>, not <source network='default'/>, for type='bridge'. |
Refusing to undefine while domain managed save image exists |
virsh managedsave-remove vm01, or undefine with --managed-save. |
error: Active console session exists for this domain |
Close the other virsh console session. |
| Console shows nothing | No serial console in the guest; see Details. |
| VM will not boot after a resize attempt | qemu-img check disk.qcow2; restore from a snapshot or backup. |
Old Debian/BIOS guest hangs at unaligned pointer |
Change the video model from qxl to vga (Debian bug 652593). |
virt-install fails with --graphics none |
The installer or OS does not support a serial console; use VNC/SPICE instead. |