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This article describes the Win 12B issue that impacts SDN-based SCVMM deployments and also provides the resolution and FAQs related to the issue. 

Known Issue

Installation of Windows 12B patch (KB 5021249 and KB 5021237 dated 13-Dec-2022) on an SCVMM managed Windows Server/Azure Stack HCI Host with Software Defined Networking (SDN) is seen to cause the following issues: 

  • New VM creation fails: Creating a new VM with Network adapter fails.

  • SLB Load Balancer or SDN RAS Gateway fails with an EthernetConnection error.

  • Attaching vNIC fails: Attaching a Network adapter to an existing VM fails.

  • Warning message during live migration: Live migration of Non-Highly Available VMs completes with an EthernetConnection warning message.

An error message like the one below is seen in these scenarios: 

Error (12700)
VMM cannot complete the host operation on the 'cdmrr46r09n03.cdm.lab' server because of the error: 'TestRs5' failed to modify device 'Ethernet Connection'. 

Impacted Scenarios/Environments

  • SCVMM managed Windows Server or Azure Stack HCI Hosts.

  • Software Defined Networking (SDN) enabled with Network Controller (NC).

  • Host OS: Windows Server 2019/2022 or Azure Stack HCI with Windows patch 12B applied.


A fix for this issue is available through the Microsoft Update Catalog as outlined below. 


If you encountered the above issues after patching SCVMM managed Hyper-V hosts with KB 5021249 and KB 5021237, we recommend installing the appropriate Cumulative update from below on all SCVMM managed hosts. 

If you haven’t patched SCVMM managed Hyper-V hosts with KB 5021249 and KB 5021237 updates, we recommend skipping the updates KB 5021249 and KB 5021237 and manually installing the following Cumulative updates on all SCVMM managed hosts. 

Cumulative Updates

  • Windows Server 2022:  KB5022553  -  Link to download the KB from Microsoft Update Catalog

  • Windows Server 2019:  KB5022554  - Link to download the KB from Microsoft Update Catalog 


  • The cumulative update(s) above will resolve this issue even if it has already been encountered from an upgrade to the 12B release. Additional workarounds or scripts are not necessary.

  • The above updates are not available from Windows Update and will not be installed automatically. You can manually import these updates into Windows Server Update Services (WSUS) and Microsoft Endpoint Configuration Manager. For WSUS updates, see WSUS and the Catalog Site. For Microsoft Endpoint Configuration Manager updates, see Import updates from the Microsoft Update Catalog.

Frequently Asked Questions

1. I don't use SCVMM. Is my Windows Server/AzStack HCI Host affected by this issue? 

Ans: No, this issue is only seen with SCVMM Managed Windows Server/AzStack HCI hosts. 

2. I don't use Software Defined Networking/Network Controller in SCVMM. Is this issue applicable? 

Ans: No, this issue is applicable only with SDN-enabled SCVMM environments. 

3. Is Windows Server 2016 affected by this issue? 

Ans: No, this issue has only been observed with Windows Server 2022/2019, and not 2016. 

4. Is this issue applicable to SCVMM managed Azure Stack HCI Hosts? 

Ans: Yes, this issue is applicable to Azure Stack HCI Hosts managed by SCVMM with SDN. 

5. I updated a Guest VM in my SCVMM environment with the 12B patch. Is my SCVMM environment affected? 

Ans: No, this issue is relevant only to Hosts and not to Guest VMs. 

6. I updated my SCVMM Management Server machine with the 12B patch. Is my SCVMM environment affected? 

Ans: No, this issue is relevant only to Hosts and not to the SCVMM Management Server machine. 

7. I have uninstalled the Windows 12B patch. Is my SCVMM environment still impacted? 

Ans: Yes, the issue will persist even after the 12B patch is uninstalled. The cumulative updates KB5022553 and KB5022554 are required for resolving this issue. 

8. Are existing VMs or VMs migrated after the 12B update affected due to this issue? 

Ans: No, there is no impact on network connectivity of the existing VMs or for VM Migration after applying the 12B patch. Only new VMs or new Network adapter connections on existing VMs are seen to be affected. With live migration of non-HA VMs, an EthernetConnection warning may be seen, but there is no functional impact on network connectivity. 

9. If I install KB5022553/KB5022554, do I still need to install the 12B update? 

Ans: No, since these are cumulative updates, the updates from 12B are also available in the fix. 

10. There were workaround scripts available earlier for this issue. Are these still required? 

Ans: No, the workaround scripts are no longer required. 

11. I have already encountered this issue; will the fix versions resolve the issue?

Ans: Yes, the fix will resolve the issue if already encountered and prevent further recurrence. 

12. I need more assistance on this issue. How do I reach out?

Ans: Please reach out to Microsoft Support team by opening a support request.

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