Re-registering vCenter server with NSX-T after the NSX-T manager re-deployed

Recently, I had to redeploy the NSX-T manager node due to some issue in the lab environment. After re-deploying the new NSX-T manager 2.4.0, I noticed that the compute manager (vCenter) was not getting registered properly. I was using the old vCenter server itself which was already registered once with the OLD NSX-T manager. In this blog post, I will share details about how I resolved the issue.

Symptom :

After reinstalling the NSX-T manager, I added the vCenter server as compute manager. However, as you see in the below screenshot, the registration status was “Not Registered” and connection status was Down.

If you try to add transport node, there are no hosts listed that are managed by the vCenter server added.

Then I checked the vCenter server extensions by logging into the vCenter server via vSphere client and we see the old NSX-T manager is still registered with the vCenter.

Resolution :

To resolve the issue, we have to un-register the OLD NSX-T Extension from the vCenter Managed Object Browser(MOB) page.

Log into the vCenter MOB page by accessing https://vcsa-fqdn-or-ip-address/mob/ . You will have to provide the SSO administrator username and password to login to the vCenter mob page. Once you are in the home page of MOB, click on content.

Now, click on ExtensionManager.

Click more to see all the extensions registered with the vCenter.

You will see the NSX-T manager Extension registered. Click on the NSX-T Extension to see more details.

Make a note of the key string from the Properties page.

Go back to the ExtensionManager page and click on the UnregisterExtension link.

Paste the string copied from the previous window into the Value field in the UnregisterExtension tool. Click on Invoke Method.

Once completed, you will see the confirmation.

Go back to the vCenter Server Extensions page, and confirm the NSX-T manager extension is un-registered.

Login to the NSX-T manager GUI > System > Fabric > Compute Managers. Delete the old vcsa and add it again. This time you can see the vCenter registration is successful and the connection status is up as in the below screenshot.

Go to the Host Transport Nodes page, click on the Managed by drop down and select the vcsa added. You will now be able to see the clusters from the vCenter available under the nodes.