NSX Compute Manager status shows as Down following a vCenter Server upgrade

Products

• VMware vCenter Server
• VMware NSX

Issue/Introduction

After upgrading a registered vCenter Server (e.g., from 7.0 to 8.0), the Compute Manager status within the NSX Manager UI may report as "Connection down." Although network connectivity between the NSX Manager and vCenter Server is functional, the management plane synchronization is interrupted. The Machine SSL thumbprint in NSX appears to match the one on the Upgraded vCenter

• In the NSX Manager UI, under System > Fabric > Compute Managers, the status is "Down."

• The vCenter version displayed in the NSX metadata remains at the pre-upgrade version.

• Errors indicating a failure to establish a connection or a version mismatch may be present in the management logs.
  
  

Environment

• VMware Cloud Foundation
• NSX 4.x
• VMware vCenter Server 8.0, 7.0

Cause

The underlying cause is the retention of stale vCenter metadata and cached connection states within the NSX Manager inventory process. The NSX Manager does not automatically refresh the vCenter version information following an out-of-band upgrade, leading to a handshake failure between the management components.

Resolution

To resolve this issue, the NSX Manager service must be restarted to force a re-initialization of the Compute Manager connection.

1. Log in to the NSX Manager CLI as admin via SSH.

2. Verify the current state of the manager service:

   get service manager

3. Restart the manager service:

   restart service manager

   Note: This will temporarily interrupt access to the NSX Manager UI and API but will not impact data plane traffic.

4. Wait several minutes for the service to initialize.

5. Log back into the NSX Manager UI.

6. Navigate to System > Fabric > Compute Managers and verify that the status has transitioned to "Up" and the vCenter version is correctly reflected

 

Additional Information

Note: The Same symptom is experienced if Post Upgrading the vCenter Certificate the SSL thumbprint is changed. 
If this issue occurs post Renewing the vCenter cerificates, please refer to After the vCenter Server certificate is replaced, the compute manager connection is "Down" in the NSX UI