Environment: Devel env, last commit's hash: 358b5ddfec2cf6389f009032c852f000d95b4fc8 The Network's drop-down list in "New Network Interface" dialog which appears when adding nic to vm sometimes warns "This field can't be empty" and colors the list's border in orange, it ususlly happens when adding nic relatively fast.
Created attachment 556300 [details] Screenshot
should be taken care of as part of the new setup-networks GUI.
fixed in commit 3351a89c094532fb85a0ab1815add7f389698540
closing ON_QA bugs as oVirt 3.1 was released: http://www.ovirt.org/get-ovirt/