Recently, a few SDN customers have hit an issue where after updating their SDN environments with patches, SDN stops working. This issue has been fixed in the latest update (KB4487006). All customers are strongly recommended to this update to this KB if they have already encountered this issue, or as a part of their next regular patch cycle.
Applicable to: Windows Server 2016 customers who have deployed SDN
When will the issue occur: Any SDN customers who were on KB4343884, KB4457131, KB4457127, KB4462917 and have upgraded to any newer patches will no longer be able to communicate with their network controller. This will be visible as errors when using Network Controller PowerShell commands, or Network Controller errors in SC VMM.
How to identify that you have hit this issue: If you have hit this issue, the sdnapi microservice replica state keeps moving from "Primary" to "Down" to "InBuild". The long term/steady state should be "Ready". To get the status of the sdnapi service, run the following Powershell command on any of the Network Controller VMs: Get-NetworkControllerReplica -ServiceTypeName "ApiService"
If you look at Network Controller logs (located at C:\Windows\tracing\SDNDiagnostics\logs), you will see a pattern similar to the below:
SDNAPI... Primary Recovery Failed: System.ArgumentException: Unable to deserialize unknown property "storage_Epoch" in class "Microsoft.Windows.Networking.NetworkController.EventCoordinator.VirtualInterfaceState".
Impact of the issue: Communication between customer tenant VMs will stop working if any of the VMs are moved to a different host or if the host goes down. Management and configuration of the fabric or tenant networks will be unavailable.
Resolution: The issue has been fixed in the latest Microsoft update (KB4487006). All customers are strongly recommended to move to the latest updates. After installing this update, no further steps are required to resolve this issue.