NSX upgrade failure for the Hosts with the error Unexpected error while upgrading upgrade unit: Host https://https:/XXXXX/ssdk not reachable. java.net.NoRouteToHostExcepti on: No route to host (Host unreachable)

Products

• VMware NSX

Issue/Introduction

During an NSX upgrade, the host upgrade process fails with an unexpected error on the Upgrade Unit.

You will observe the following error message in the upgrade logs or UI:

Errorr: Unexpected error while upgrading upgrade unit: Host https://https:/XXXXX/ssdk not reachable. java.net.NoRouteToHostExcepti on: No route to host (Host unreachable)

Additionally, you may observe the following symptoms in your environment:

• Under Host Transport Nodes in the NSX UI, the host status stays in a Pending state.

• Tunnels show as Not available.

Network connectivity between the ESXi host and NSX Managers may appear healthy:

• Running a Netcat test (nc -z <Manager-IP> 1234 and 1235) succeeds.

• Running the command get managers from the host's nsxcli shows that all managers are successfully connected from the ESXi host.

During the upgrade, the NSX Manager attempts to reach the ESXi host via the IP address mentioned in the error message . Analysis of the VMkernel configuration reveals that this IP address belongs to the vSAN VMkernel interface (e.g., vmk2), rather than the dedicated Management interface.

 

Environment

VMware NSX

Cause

This issue occurs due to a VMkernel adapter misconfiguration on the affected ESXi host, causing the NSX Manager to attempt communication over an unreachable interface.

Because the Management service tag was incorrectly enabled on the vSAN VMkernel adapter alongside the vSAN service, NSX Manager incorrectly selected this IP for upgrade communication, leading to a routing failure.

Resolution

To resolve this issue, you must correct the VMkernel adapter service tags on the affected ESXi host so that the NSX Manager communicates over the proper management network.

 

• Log in to the vSphere Client or directly to the affected ESXi host.

• Navigate to the host's Networking configuration and review the VMkernel adapters.

• Check the enabled services on the adapter utilizing the IP address mentioned in the error message (e.g., the vSAN VMK).

• Edit the VMkernel adapter settings and remove the Management service checkbox.

• Ensure that only the intended service (e.g., Management) remains enabled for that specific adapter.

• Once the VMkernel configuration is corrected, return to the NSX Manager UI and retry the host upgrade. The upgrade should now complete successfully.