Paul, would you provide the precise versions of your ovirt-engine, vdsm and ovirt-hosted-engine-setup?

Artyom, can you reproduce this in a current build?

I do not see such problem in my environment.
rhvm-4.2.1.1-0.1.el7.noarch

[root@engine ~]# rpm -qa | grep ovirt-engine
ovirt-engine-tools-backup-4.2.0.2-1.el7.centos.noarch
ovirt-engine-backend-4.2.0.2-1.el7.centos.noarch
ovirt-engine-metrics-1.1.1-1.el7.centos.noarch
ovirt-engine-webadmin-portal-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-plugin-websocket-proxy-4.2.0.2-1.el7.centos.noarch
ovirt-engine-dwh-setup-4.2.1-1.el7.centos.noarch
ovirt-engine-dbscripts-4.2.0.2-1.el7.centos.noarch
ovirt-engine-restapi-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-plugin-vmconsole-proxy-helper-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-4.2.0.2-1.el7.centos.noarch
ovirt-engine-dashboard-1.2.0-1.el7.centos.noarch
ovirt-engine-api-explorer-0.0.2-1.el7.centos.noarch
ovirt-engine-tools-4.2.0.2-1.el7.centos.noarch
ovirt-engine-extensions-api-impl-4.2.0.2-1.el7.centos.noarch
ovirt-engine-cli-3.6.9.2-1.el7.centos.noarch
ovirt-engine-lib-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-base-4.2.0.2-1.el7.centos.noarch
ovirt-engine-wildfly-overlay-11.0.1-1.el7.centos.noarch
ovirt-engine-setup-plugin-ovirt-engine-common-4.2.0.2-1.el7.centos.noarch
ovirt-engine-websocket-proxy-4.2.0.2-1.el7.centos.noarch
ovirt-engine-dwh-4.2.1-1.el7.centos.noarch
ovirt-engine-vmconsole-proxy-helper-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-plugin-ovirt-engine-4.2.0.2-1.el7.centos.noarch
ovirt-engine-4.2.0.2-1.el7.centos.noarch
python-ovirt-engine-sdk4-4.2.2-2.el7.centos.x86_64
ovirt-engine-extension-aaa-jdbc-1.1.6-1.el7.centos.noarch
ovirt-engine-sdk-python-3.6.9.1-1.el7.noarch
ovirt-engine-wildfly-11.0.0-1.el7.centos.x86_64

[root@host01 ~]# rpm -qa | grep hosted-engine
ovirt-hosted-engine-setup-2.2.3-1.el7.centos.noarch
ovirt-hosted-engine-ha-2.2.2-1.el7.centos.noarch

[root@host01 ~]# rpm -qa | grep vdsm
vdsm-client-4.20.9.3-1.el7.centos.noarch
vdsm-hook-ethtool-options-4.20.9.3-1.el7.centos.noarch
vdsm-http-4.20.9.3-1.el7.centos.noarch
vdsm-hook-openstacknet-4.20.9.3-1.el7.centos.noarch
vdsm-yajsonrpc-4.20.9.3-1.el7.centos.noarch
vdsm-python-4.20.9.3-1.el7.centos.noarch
vdsm-hook-vmfex-dev-4.20.9.3-1.el7.centos.noarch
vdsm-hook-vhostmd-4.20.9.3-1.el7.centos.noarch
vdsm-api-4.20.9.3-1.el7.centos.noarch
vdsm-4.20.9.3-1.el7.centos.x86_64
vdsm-hook-vfio-mdev-4.20.9.3-1.el7.centos.noarch
vdsm-jsonrpc-4.20.9.3-1.el7.centos.noarch
vdsm-hook-fcoe-4.20.9.3-1.el7.centos.noarch

I get a similar exception when i want to view the "Snapshot" tab:

"Uncaught exception occurred. Please try reloading the page. Details: Exception caught: (TypeError) : h.M is null
Please have your administrator check the UI logs"

Log /var/log/ovirt-engine/ui.log:
2018-01-24 15:01:20,756+01 ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-54) [] Permutation name: 31107359ADCBCFB59694E16AF69E391A
2018-01-24 15:01:20,757+01 ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-54) [] Uncaught exception: com.google.gwt.core.client.JavaScriptException: (TypeError) : h.M is null
        at org.ovirt.engine.ui.common.widget.uicommon.vm.VmSnapshotListViewItem.$createNicsItemContainerPanel(VmSnapshotListViewItem.java:90)
        at org.ovirt.engine.ui.common.widget.uicommon.vm.VmSnapshotListViewItem.$updateValues(VmSnapshotListViewItem.java:387)
        at org.ovirt.engine.ui.common.widget.uicommon.vm.VmSnapshotListViewItem.VmSnapshotListViewItem(VmSnapshotListViewItem.java:63)
        at org.ovirt.engine.ui.webadmin.section.main.view.tab.virtualMachine.SubTabVirtualMachineSnapshotView.$createListViewItem(SubTabVirtualMachineSnapshotView.java:68)
        at org.ovirt.engine.ui.webadmin.section.main.view.tab.virtualMachine.SubTabVirtualMachineSnapshotView.createListViewItem(SubTabVirtualMachineSnapshotView.java:68)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView.$updateInfoPanel(PatternflyListView.java:137)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView.$lambda$1(PatternflyListView.java:63)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView$lambda$1$Type.eventRaised(PatternflyListView.java:63)
        at org.ovirt.engine.ui.uicompat.Event.$raise(Event.java:99)
        at org.ovirt.engine.ui.uicommonweb.models.SearchableListModel.$setItems(SearchableListModel.java:739)
        at org.ovirt.engine.ui.uicommonweb.models.vms.VmSnapshotListModel.$updateItems(VmSnapshotListModel.java:230)
        at org.ovirt.engine.ui.uicommonweb.models.vms.VmSnapshotListModel.setItems(VmSnapshotListModel.java:209)
        at org.ovirt.engine.ui.uicommonweb.models.SearchableListModel$SetItemsAsyncQuery$1.$onSuccess(SearchableListModel.java:902)
        at org.ovirt.engine.ui.uicommonweb.models.SearchableListModel$SetItemsAsyncQuery$1.onSuccess(SearchableListModel.java:902)
        at org.ovirt.engine.ui.frontend.Frontend$1.$onSuccess(Frontend.java:227) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.Frontend$1.onSuccess(Frontend.java:227) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.OperationProcessor$1.$onSuccess(OperationProcessor.java:133) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.OperationProcessor$1.onSuccess(OperationProcessor.java:133) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.GWTRPCCommunicationProvider$3$1.$onSuccess(GWTRPCCommunicationProvider.java:161) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.GWTRPCCommunicationProvider$3$1.onSuccess(GWTRPCCommunicationProvider.java:161) [frontend.jar:]
        at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:198) [gwt-servlet.jar:]
        at com.google.gwt.http.client.Request.$fireOnResponseReceived(Request.java:233) [gwt-servlet.jar:]
        at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:409) [gwt-servlet.jar:]
        at Unknown.onreadystatechange<(https://localhost:4443/ovirt-engine/webadmin/?locale=en_US#dashboard-main)
        at com.google.gwt.core.client.impl.Impl.apply(Impl.java:236) [gwt-servlet.jar:]
        at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:275) [gwt-servlet.jar:]
        at Unknown.Ju/<(https://localhost:4443/ovirt-engine/webadmin/?locale=en_US#dashboard-main)
        at Unknown.anonymous(Unknown)

Same thing here when accessing the network interfaces OR snapshots tab of a VM.

Versions:
ovirt-engine-4.2.0.2-1.el7.centos.noarch
ovirt-web-ui-1.3.4-1.el7.centos.noarch



2018-01-30 09:01:42,718Z ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-40) [] Permutation name: 31107359ADCBCFB59694E16AF69E391A
2018-01-30 09:01:42,719Z ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-40) [] Uncaught exception: com.google.gwt.core.client.JavaScriptException: (TypeError) : a.M is null
        at org.ovirt.engine.ui.common.widget.uicommon.vm.VmInterfaceListGroupItem.VmInterfaceListGroupItem(VmInterfaceListGroupItem.java:53)
        at org.ovirt.engine.ui.webadmin.section.main.view.tab.virtualMachine.SubTabVirtualMachineNetworkInterfaceView.$createListViewItem(SubTabVirtualMachineNetworkInterfaceView.java:69)
        at org.ovirt.engine.ui.webadmin.section.main.view.tab.virtualMachine.SubTabVirtualMachineNetworkInterfaceView.createListViewItem(SubTabVirtualMachineNetworkInterfaceView.java:69)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView.$updateInfoPanel(PatternflyListView.java:137)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView.$lambda$1(PatternflyListView.java:63)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView$lambda$1$Type.eventRaised(PatternflyListView.java:63)
        at org.ovirt.engine.ui.uicompat.Event.$raise(Event.java:99)
        at org.ovirt.engine.ui.uicommonweb.models.SearchableListModel.$setItems(SearchableListModel.java:739)
        at org.ovirt.engine.ui.uicommonweb.models.vms.VmInterfaceListModel.$lambda$2(VmInterfaceListModel.java:143)
        at org.ovirt.engine.ui.uicommonweb.models.vms.VmInterfaceListModel$lambda$2$Type.executed(VmInterfaceListModel.java:143)
        at org.ovirt.engine.ui.frontend.Frontend$2.$onSuccess(Frontend.java:319) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.Frontend$2.onSuccess(Frontend.java:319) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.OperationProcessor$2.$onSuccess(OperationProcessor.java:170) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.OperationProcessor$2.onSuccess(OperationProcessor.java:170) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.GWTRPCCommunicationProvider$5$1.$onSuccess(GWTRPCCommunicationProvider.java:270) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.GWTRPCCommunicationProvider$5$1.onSuccess(GWTRPCCommunicationProvider.java:270) [frontend.jar:]
        at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:198) [gwt-servlet.jar:]
        at com.google.gwt.http.client.Request.$fireOnResponseReceived(Request.java:233) [gwt-servlet.jar:]
        at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:409) [gwt-servlet.jar:]
        at Unknown.onreadystatechange<(https://ovirt-hc0.arsyslan.es/ovirt-engine/webadmin/?locale=en_US#vms-network_interfaces)
        at com.google.gwt.core.client.impl.Impl.apply(Impl.java:236) [gwt-servlet.jar:]
        at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:275) [gwt-servlet.jar:]
        at Unknown.Ju/<(https://ovirt-hc0.arsyslan.es/ovirt-engine/webadmin/?locale=en_US#vms-network_interfaces)
        at Unknown.anonymous(Unknown)

I do see a minor difference in the version numbers of the tested engines:
- Eduardo and I have ovirt-engine-4.2.0.2-1.el7.centos.noarch
- Atryom has rhvm-4.2.1.1-0.1.el7.noarch. 

Would it be possible this explains the different experiences?
I tried to update to the latest engine version available but both "engine-upgrade-check" and "engine-setup" claimed all latest versions are already installed.

For me the ovirt environment is next to useless without proper configuration of the hosted engine with networkinterfaces. The impact for me is very high. Postponing this to 4.3 would probably take a while. This makes version 4.2 a missed oppertunity, which is a shame for this wonderfull product.

Is there any way we can help/contribute to fix this seemingly minor error in the interface?

*** Bug 1535600 has been marked as a duplicate of this bug. ***

@Artyom, you used hosted engine, right?

(In reply to paul from comment #6)

> Would it be possible this explains the different experiences?

I think Artyom was using pre-release software. You could try the latest 4.2.1 RC
https://www.mail-archive.com/users@ovirt.org/msg45929.html (but not in production)

> Is there any way we can help/contribute to fix this seemingly minor error in
> the interface?

If you're a developer, patches are always welcome :)
https://www.ovirt.org/develop/

Basically it looks like PatternflyListView is expecting some information, and in the HE scenario, a variable somewhere is null. "a.M is null" means NPE.

@greg I am not using hosted engine (My oVirt engine is a vanilla CentOS 7.4 hosted outside of oVirt), and I am seeing the same error.

(In reply to Eduardo Mayoral from comment #9)
> @greg I am not using hosted engine (My oVirt engine is a vanilla CentOS 7.4
> hosted outside of oVirt), and I am seeing the same error.

Thanks, good to know

I noticed this does not happen with all my VMs, only some of them, always the same ones. I am trying to figure out what the difference among the ones which show the error and the ones which don't.

I think the ones with the error are precisely the ones with the virtual NIC in one of the virtual networks. I have 3 service virtual networks, only the ones connected to that network sow the problem.

As far as I can see, other than the name and the VLAN, the 3 virtual networks are identical.

Yes, correct I used hosted-engine environment.

I am seeing this pop up, too, when trying to go "Network Interfaces" of the hosted-engine VM:

"Uncaught exception occurred. Please try reloading the page. Details: (TypeError): Cannot read property 'a' of null Please have your Adminstrator check the UI logs"

From ui.log:

2018-02-05 08:07:27,615-05 ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-28) [] Permutation name: C1D1FEFE5DCAE683818762C75C501D92
2018-02-05 08:07:27,615-05 ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-28) [] Uncaught exception: com.google.gwt.core.client.JavaScriptException: (TypeError) : Cannot read property 'a' of null
        at Unknown.new pvp(webadmin-141.js)
        at org.ovirt.engine.ui.webadmin.section.main.view.tab.virtualMachine.SubTabVirtualMachineNetworkInterfaceView.$createListViewItem(SubTabVirtualMachineNetworkInterfaceView.java:69)
        at org.ovirt.engine.ui.webadmin.section.main.view.tab.virtualMachine.SubTabVirtualMachineNetworkInterfaceView.createListViewItem(SubTabVirtualMachineNetworkInterfaceView.java:69)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView.$updateInfoPanel(PatternflyListView.java:137)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView.$lambda$1(PatternflyListView.java:63)
        at org.ovirt.engine.ui.common.widget.listgroup.PatternflyListView$lambda$1$Type.eventRaised(PatternflyListView.java:63)
        at org.ovirt.engine.ui.uicompat.Event.$raise(Event.java:99)
        at org.ovirt.engine.ui.uicommonweb.models.SearchableListModel.$setItems(SearchableListModel.java:739)
        at org.ovirt.engine.ui.uicommonweb.models.vms.VmInterfaceListModel.$lambda$2(VmInterfaceListModel.java:143)
        at org.ovirt.engine.ui.uicommonweb.models.vms.VmInterfaceListModel$lambda$2$Type.executed(VmInterfaceListModel.java:143)
        at org.ovirt.engine.ui.frontend.Frontend$2.$onSuccess(Frontend.java:319) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.Frontend$2.onSuccess(Frontend.java:319) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.OperationProcessor$2.$onSuccess(OperationProcessor.java:170) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.OperationProcessor$2.onSuccess(OperationProcessor.java:170) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.GWTRPCCommunicationProvider$5$1.$onSuccess(GWTRPCCommunicationProvider.java:270) [frontend.jar:]
        at org.ovirt.engine.ui.frontend.communication.GWTRPCCommunicationProvider$5$1.onSuccess(GWTRPCCommunicationProvider.java:270) [frontend.jar:]
        at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:198) [gwt-servlet.jar:]
        at com.google.gwt.http.client.Request.$fireOnResponseReceived(Request.java:233) [gwt-servlet.jar:]
        at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:409) [gwt-servlet.jar:]
        at Unknown.eval(webadmin-0.js)
        at com.google.gwt.core.client.impl.Impl.apply(Impl.java:236) [gwt-servlet.jar:]
        at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:275) [gwt-servlet.jar:]
        at Unknown.eval(webadmin-0.js)


[root@ovirt-engine ovirt-engine]# rpm -qa | grep ovirt-engine
ovirt-engine-tools-backup-4.2.0.2-1.el7.centos.noarch
ovirt-engine-backend-4.2.0.2-1.el7.centos.noarch
ovirt-engine-metrics-1.1.1-1.el7.centos.noarch
ovirt-engine-webadmin-portal-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-plugin-websocket-proxy-4.2.0.2-1.el7.centos.noarch
ovirt-engine-dwh-setup-4.2.1-1.el7.centos.noarch
ovirt-engine-dbscripts-4.2.0.2-1.el7.centos.noarch
ovirt-engine-restapi-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-plugin-vmconsole-proxy-helper-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-4.2.0.2-1.el7.centos.noarch
ovirt-engine-dashboard-1.2.0-1.el7.centos.noarch
ovirt-engine-api-explorer-0.0.2-1.el7.centos.noarch
ovirt-engine-tools-4.2.0.2-1.el7.centos.noarch
ovirt-engine-extensions-api-impl-4.2.0.2-1.el7.centos.noarch
ovirt-engine-cli-3.6.9.2-1.el7.centos.noarch
ovirt-engine-lib-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-base-4.2.0.2-1.el7.centos.noarch
ovirt-engine-wildfly-overlay-11.0.1-1.el7.centos.noarch
ovirt-engine-setup-plugin-ovirt-engine-common-4.2.0.2-1.el7.centos.noarch
ovirt-engine-websocket-proxy-4.2.0.2-1.el7.centos.noarch
ovirt-engine-dwh-4.2.1-1.el7.centos.noarch
ovirt-engine-vmconsole-proxy-helper-4.2.0.2-1.el7.centos.noarch
ovirt-engine-setup-plugin-ovirt-engine-4.2.0.2-1.el7.centos.noarch
ovirt-engine-4.2.0.2-1.el7.centos.noarch
python-ovirt-engine-sdk4-4.2.2-2.el7.centos.x86_64
ovirt-engine-extension-aaa-jdbc-1.1.6-1.el7.centos.noarch
ovirt-engine-sdk-python-3.6.9.1-1.el7.noarch
ovirt-engine-wildfly-11.0.0-1.el7.centos.x86_64
[root@ovirt-engine ovirt-engine]#

[root@on2 ~]# rpm -qa | grep hosted-engine
ovirt-hosted-engine-ha-2.2.2-1.el7.centos.noarch
ovirt-hosted-engine-setup-2.2.3-1.el7.centos.noarch
[root@on2 ~]#

[root@on2 ~]# rpm -qa | grep vdsm
vdsm-hook-ethtool-options-4.20.9.3-1.el7.centos.noarch
vdsm-api-4.20.9.3-1.el7.centos.noarch
vdsm-jsonrpc-4.20.9.3-1.el7.centos.noarch
vdsm-hook-vfio-mdev-4.20.9.3-1.el7.centos.noarch
vdsm-client-4.20.9.3-1.el7.centos.noarch
vdsm-gluster-4.20.9.3-1.el7.centos.noarch
vdsm-hook-openstacknet-4.20.9.3-1.el7.centos.noarch
vdsm-yajsonrpc-4.20.9.3-1.el7.centos.noarch
vdsm-python-4.20.9.3-1.el7.centos.noarch
vdsm-hook-vmfex-dev-4.20.9.3-1.el7.centos.noarch
vdsm-4.20.9.3-1.el7.centos.x86_64
vdsm-hook-vhostmd-4.20.9.3-1.el7.centos.noarch
vdsm-http-4.20.9.3-1.el7.centos.noarch
vdsm-hook-fcoe-4.20.9.3-1.el7.centos.noarch
[root@on2 ~]#

With the recent upgrade to ovirt-engine-4.2.1.6-1.el7.centos.noarch this bug disappeared for me :-)

This is consistent with Artyom not seeing the bug in rhvm-4.2.1.1-0.1.el7.noarch