Unable to register compute manager to NSX due to stale extension

Products

• VMware NSX

Issue/Introduction

• An error occurs when attempting to add a compute manager to NSX stating that the compute manager is already registered with another NSX manager.

Error: "Compute manager <name> is already registered with other NSX manager <IP:port>" 

             

• Compute manager Registration status shows 'Not Registered' and Connection Status as "Down"

           

• The error message references to a decommissioned NSX manager which was earlier attached to this vCenter.

• A stale extension named com.vmware.nsx.management.nsxt is visible in the vCenter managed object browser.

• A stale extension named com.vmware.nsx.management.nsxt.vcp is visible in the vCenter managed object browser.

 

Environment

VMware NSX

Cause

This issue occurs when the previous NSX manager is decommissioned without properly unregistering the vCenter server.The stale NSX extension from the previous instance remains on the vCenter and prevents the association with a new manager.

Resolution

To resolve this conflict, you must manually remove the stale extension using the vCenter Managed Object Browser (MOB).

Prerequisite: Access to the vCenter Managed Object Browser (MOB) must be enabled. Please refer to Broadcom KB 403417 for instructions on enabling MOB access.

Steps to Remove the Stale Extension:

1. 1. Log in to the vCenter Managed Object Browser (MOB)

   • Open a web browser and navigate to: https://<vCenter_Server_IP_or_FQDN>/mob

   • Log in using your vCenter Server administrator credentials (e.g., [e-mail]).

   2. Navigate to Extension Manager

   • Click the content link located in the Properties table.

   • Click the ExtensionManager link located within the Properties table.

   3. Unregister the NSX Extensions

   • Locate the Methods table at the bottom of the page.

   • Click the link for UnregisterExtension.

   • Remove Primary Extension:

     • In the value field, enter: com.vmware.nsx.management.nsxt

     • Click Invoke Method to remove the extension.

   • Remove VCP Extension:

     • In the value field, enter: com.vmware.nsx.management.nsxt.vcp

     • Click Invoke Method to remove the extension.

   4. Verify Removal

   • Return to the ExtensionManager page.

   • Click the FindExtension link.

   • Check both extension keys individually:

     1. Enter com.vmware.nsx.management.nsxt in the value field and click Invoke Method.

     2. Enter com.vmware.nsx.management.nsxt.vcp in the value field and click Invoke Method.

   • Expected Result: Both invocations should return void (or NotFound/null), confirming that neither stale extension key remains in the vCenter configuration.

   5. Retry Operation

   • Return to the NSX Manager UI.

   • Navigate to System > Compute Managers.

   • Attempt to add or re-register the vCenter Server as a Compute Manager.

Additional Information

If you still face the issue, please open a support case with Broadcom Support and refer to this KB article.

For more information, see Creating and managing Broadcom support cases.

 

Additional Information

Reference   :
1. Tech docs:Remove NSX Extension from vCenter