The web-based console of a host provisioned as a (Libvirt) VM cannot be used when the VNC keymap of the VM has been changed from "auto" to something else (by means of virt-manager or virsh). Clicking on "Console" fails with this error message:

Failed to set console: Call to virDomainUpdateDeviceFlags failed: internal error cannot change keymap setting on vnc graphics

The same message is visible in the Libvirt host's logs:

2012-05-19 20:59:36.339+0000: 26184: error : qemuDomainChangeGraphics:1357 : internal error cannot change keymap setting on vnc graphics

Using Ubuntu 12.04, Libvirt 0.9.8 and Foreman 0.5-nightly-ba71c565.