Description of problem:
When adding a disk to a new VM, regardless of type, the Webadmin GUI posts an alert stating:

Uncaught exception occurred. Please try reloading the page. Details: Exception caught: Exception caught: (TypeError) 
 line: 294
 column: 38
 sourceURL: https://kt-ovirt.keepertech.com/ovirt-engine/webadmin/?locale=en_US
 __gwt$exception: <skipped>: null is not an object (evaluating 'a.b')
Please have your administrator check the UI logs

This alert happened when clicking "OK" on the pane that defines the disk settings the first time. If you click "OK" again, the disk is created, the VM can be launched, and the alert pane at the top of the GUI can just be dismissed. There does not seem to be any issue with the VM or the disk that was created while this alert was present.

The ui.log on the oVirt Engine server reads as follows:

2016-11-30 21:55:16,256 ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-122) [] Permutation name: 36FFE9E683BD2C616FFB067DABA3A81E
2016-11-30 21:55:16,257 ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-122) [] Uncaught exception: com.google.gwt.event.shared.UmbrellaException: Exception caught: Exception caught: (TypeError) 
 line: 294
 column: 38
 sourceURL: https://kt-ovirt.keepertech.com/ovirt-engine/webadmin/?locale=en_US
 __gwt$exception: <skipped>: null is not an object (evaluating 'a.b')
	at java.lang.Throwable.fillInStackTrace(Throwable.java:114) [rt.jar:1.8.0_111]
	at java.lang.RuntimeException.RuntimeException(RuntimeException.java:32) [rt.jar:1.8.0_111]
	at com.google.web.bindery.event.shared.UmbrellaException.UmbrellaException(UmbrellaException.java:70) [gwt-servlet.jar:]
	at com.google.gwt.event.shared.UmbrellaException.UmbrellaException(UmbrellaException.java:25) [gwt-servlet.jar:]
	at com.google.gwt.event.shared.HandlerManager.$fireEvent(HandlerManager.java:117) [gwt-servlet.jar:]
	at com.google.gwt.user.client.ui.Widget.$fireEvent(Widget.java:127) [gwt-servlet.jar:]
	at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:127) [gwt-servlet.jar:]
	at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:110) [gwt-servlet.jar:]
	at com.google.gwt.user.client.ui.Widget.$onBrowserEvent(Widget.java:163) [gwt-servlet.jar:]
	at com.google.gwt.user.client.ui.CustomButton.onBrowserEvent(CustomButton.java:631) [gwt-servlet.jar:]
	at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1648) [gwt-servlet.jar:]
	at com.google.gwt.user.client.impl.DOMImplStandard.dispatchEvent(DOMImplStandard.java:320) [gwt-servlet.jar:]
	at com.google.gwt.core.client.impl.Impl.apply(Impl.java:296) [gwt-servlet.jar:]
	at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:335) [gwt-servlet.jar:]
	at Unknown.anonymous(https://kt-ovirt.keepertech.com/ovirt-engine/webadmin/?locale=en_US@56)
	at Unknown.dispatchEvent(Unknown@-1)
	at com.google.gwt.dom.client.DOMImplStandard.$dispatchEvent(DOMImplStandard.java:68) [gwt-servlet.jar:]
	at com.google.gwt.user.client.ui.CustomButton.$onClick(CustomButton.java:822) [gwt-servlet.jar:]
	at org.ovirt.engine.ui.common.widget.dialog.AbstractDialogButton.onClick(AbstractDialogButton.java:45)
	at com.google.gwt.user.client.ui.CustomButton.onBrowserEvent(CustomButton.java:631) [gwt-servlet.jar:]
	at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1648) [gwt-servlet.jar:]
	at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1666) [gwt-servlet.jar:]
	at com.google.gwt.user.client.impl.DOMImplStandard.dispatchCapturedMouseEvent(DOMImplStandard.java:352) [gwt-servlet.jar:]
	at com.google.gwt.core.client.impl.Impl.apply(Impl.java:296) [gwt-servlet.jar:]
	at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:335) [gwt-servlet.jar:]
	at Unknown.anonymous(https://kt-ovirt.keepertech.com/ovirt-engine/webadmin/?locale=en_US@56)
Caused by: com.google.gwt.event.shared.UmbrellaException: Exception caught: (TypeError) 
 line: 294
 column: 38
 sourceURL: https://kt-ovirt.keepertech.com/ovirt-engine/webadmin/?locale=en_US
 __gwt$exception: <skipped>: null is not an object (evaluating 'a.b')
	at java.lang.Throwable.fillInStackTrace(Throwable.java:114) [rt.jar:1.8.0_111]
	at java.lang.RuntimeException.RuntimeException(RuntimeException.java:32) [rt.jar:1.8.0_111]
	at com.google.web.bindery.event.shared.UmbrellaException.UmbrellaException(UmbrellaException.java:70) [gwt-servlet.jar:]
	at com.google.gwt.event.shared.UmbrellaException.UmbrellaException(UmbrellaException.java:25) [gwt-servlet.jar:]
	at com.google.gwt.event.shared.HandlerManager.$fireEvent(HandlerManager.java:117) [gwt-servlet.jar:]
	at com.google.gwt.user.client.ui.Widget.$fireEvent(Widget.java:127) [gwt-servlet.jar:]
	at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:127) [gwt-servlet.jar:]
	at com.google.gwt.event.logical.shared.ValueChangeEvent.fire(ValueChangeEvent.java:40) [gwt-servlet.jar:]
	at org.ovirt.engine.ui.common.widget.uicommon.instanceimages.InstanceImageLineEditor$3.eventRaised(InstanceImageLineEditor.java:96)
	at org.ovirt.engine.ui.uicompat.Event.$raise(Event.java:114)
	at org.ovirt.engine.ui.uicommonweb.models.EntityModel.$setEntity(EntityModel.java:35)
	at org.ovirt.engine.ui.uicommonweb.models.EntityModel.setEntity(EntityModel.java:35)
	at org.ovirt.engine.ui.uicommonweb.models.vms.InstanceImageLineModel$3.onSave(InstanceImageLineModel.java:270)
	at org.ovirt.engine.ui.uicommonweb.models.vms.AbstractDiskModel.executeCommand(AbstractDiskModel.java:1046)
	at org.ovirt.engine.ui.uicommonweb.UICommand.$execute(UICommand.java:163)
	at org.ovirt.engine.ui.common.presenter.AbstractModelBoundPopupPresenterWidget$6.onClick(AbstractModelBoundPopupPresenterWidget.java:337)
	at com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:55) [gwt-servlet.jar:]
	at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:76) [gwt-servlet.jar:]
	at com.google.web.bindery.event.shared.SimpleEventBus.$doFire(SimpleEventBus.java:173) [gwt-servlet.jar:]
	... 22 more
Caused by: com.google.gwt.core.client.JavaScriptException: (TypeError) 
 line: 294
 column: 38
 sourceURL: https://kt-ovirt.keepertech.com/ovirt-engine/webadmin/?locale=en_US
 __gwt$exception: <skipped>: null is not an object (evaluating 'a.b')
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget$AddRemoveRowPanel.$setButtonsEnabled(AddRemoveRowWidget.java:377)
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget.$setButtonsEnabled(AddRemoveRowWidget.java:344)
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget.toggleGhost(AddRemoveRowWidget.java:497)
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget$3.onValueChange(AddRemoveRowWidget.java:232)
	at com.google.gwt.event.logical.shared.ValueChangeEvent.dispatch(ValueChangeEvent.java:127) [gwt-servlet.jar:]
	at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:76) [gwt-servlet.jar:]
	at com.google.web.bindery.event.shared.SimpleEventBus.$doFire(SimpleEventBus.java:173) [gwt-servlet.jar:]
	... 37 more

 

Version-Release number of selected component (if applicable):


How reproducible:
Unsure; this behavior started happening following the addition of a Cinder External Provider. We do not know if that is a coincidence. We did try rolling back to the previous night's backup and the error continued to occur, despite having run engine-cleanup and having engine-backup reinstall everything.

Steps to Reproduce:
On our system at least...
1. Click "New VM"
2. Click "Create" under Instance Images
3. Set up an image as usual
4. Click "OK" and the alert is displayed at the top of the GUI page

Actual results:
No I'll effects observed for the resulting VM and image, but the alerts continue to happen for each new image created.

Expected results:
No alerts.

Additional info: