[Users] local variable 'volPath' referenced before assignment

Hi, I've updated my oVirt engine and node from version 3.1.0-2 to the more recent 3.1.0-4. As far as I can tell from the update log, the engine update went fine by following these instructions: https://www.rvanderlinden.net/wordpress/ovirt/engine-installation/engine-upg... Now I'm unable to start a VM through the Admin Portal. It fails with the following error message: VM test_srv is down. Exit message: local variable 'volPath' referenced before assignment. What's wrong? It seems this message is related to this bug report: https://bugzilla.redhat.com/show_bug.cgi?id=843387 But apparently there is no solution. What is the fix or workaround to get VMs working again? Thanks - Frank