Unable to cleate AVN by "Failed to discover resources for NSX edge cluster (policyUplinks is null)"

Products

• VMware SDDC Manager

Issue/Introduction

The user encountered the following error during the AVN setup.

Message: Failed to discover resources for NSX edge cluster [ID]
Token: [Token ID]
Cause: Cannot invoke "java.util.List.iterator()" because "policyUplinks" is null

Based on the log, the uplinkTeamingPolicy for segment ID [segment ID] was null.

/var/log/vmware/vcf/domainmanager/domainmanager.log
YYYY-MM-DDTHH:MM:SS.ZZZ+0000 DEBUG [vcf_dm,[id],0c2e] [c.v.v.c.f.p.n.a.DiscoverEdgeClusterNsxtResourcesAction,dm-exec-15]  Getting segment info for ID [Segment ID]
YYYY-MM-DDTHH:MM:SS.ZZZ+0000 DEBUG [vcf_dm,[id],0c2e] [c.v.v.c.n.s.c.c.ApiConnection,dm-exec-15]  Closed ApiClient connection.
YYYY-MM-DDTHH:MM:SS.ZZZ+0000 ERROR [vcf_dm,[id],0c2e] [c.v.e.s.o.model.error.ErrorFactory,dm-exec-15]  [[token id]] FAILED_TO_DISCOVER_EDGE_CLUSTER_RESOURCES Failed to discover resources for NSX edge cluster [cluster id]
com.vmware.evo.sddc.orchestrator.exceptions.OrchTaskException: Failed to discover resources for NSX edge cluster [cluster id]
at com.vmware.vcf.common.fsm.plugins.nsxt.action.DiscoverEdgeClusterNsxtResourcesAction.execute(DiscoverEdgeClusterNsxtResourcesAction.java:196)
at com.vmware.vcf.common.fsm.plugins.nsxt.action.DiscoverEdgeClusterNsxtResourcesAction.execute(DiscoverEdgeClusterNsxtResourcesAction.java:89)
at com.vmware.evo.sddc.orchestrator.platform.action.FsmActionState.invoke(FsmActionState.java:62)
at com.vmware.evo.sddc.orchestrator.platform.action.FsmActionPlugin.invoke(FsmActionPlugin.java:159)
at com.vmware.evo.sddc.orchestrator.platform.action.FsmActionPlugin.invoke(FsmActionPlugin.java:144)
at com.vmware.evo.sddc.orchestrator.core.ProcessingTaskSubscriber.invokeMethod(ProcessingTaskSubscriber.java:400)
at com.vmware.evo.sddc.orchestrator.core.ProcessingTaskSubscriber.processTask(ProcessingTaskSubscriber.java:520)
at com.vmware.evo.sddc.orchestrator.core.ProcessingTaskSubscriber.accept(ProcessingTaskSubscriber.java:124)
at jdk.internal.reflect.GeneratedMethodAccessor300.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:569)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:85)
at com.google.common.eventbus.Subscriber.lambda$dispatchEvent$0(Subscriber.java:71)
at com.vmware.vcf.common.tracing.TraceRunnable.run(TraceRunnable.java:59)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: java.lang.NullPointerException: Cannot invoke "java.util.List.iterator()" because "policyUplinks" is null
at com.vmware.vcf.common.fsm.plugins.nsxt.action.DiscoverEdgeClusterNsxtResourcesAction.formUplinkVlanMapToUplinkSegmentMap(DiscoverEdgeClusterNsxtResourcesAction.java:401)
at com.vmware.vcf.common.fsm.plugins.nsxt.action.DiscoverEdgeClusterNsxtResourcesAction.discoverEdgeClusterResources(DiscoverEdgeClusterNsxtResourcesAction.java:233)
at com.vmware.vcf.common.fsm.plugins.nsxt.action.DiscoverEdgeClusterNsxtResourcesAction.execute(DiscoverEdgeClusterNsxtResourcesAction.java:190)
... 16 common frames omitted

Environment

SDDC Manager 5.2
NSX Manager 4.x

Cause

There were some Out-Of-Band configurations made on the customer environment. 
The SDDC Manager AVN creation workflow is prescriptive and rigid with legitimate validations to ensure prerequisites are met.

Resolution

The added Out-Of-Band configurations need to be deleted.
If you have any questions about the deletion procedure, please open a case with Product set to NSX.