ESXi Host Fails Cluster Communication and Displays a Mismatched Web GUI

Products

• VMware vSphere ESXi

Issue/Introduction

This issue is caused by a version mismatch between the affected host and the rest of the cluster.

ESXi utilizes a dual-image boot environment. If a host experiences a critical failure during an upgrade (e.g., from ESXi 7.0 to 8.0) or suffers from bootbank corruption, it will automatically fall back to the previous working version

Environment

vSphere ESXI 7.x

vSphere ESXI 8.x

Cause

1. The ESXi host’s direct web GUI interface appears completely different (legacy or older design) compared to other nodes in the same cluster.

2. Authentication directly to the host may fail, though resetting the root password via vCenter restores access.

3. The host is unable to communicate properly with the other nodes in the cluster.

4. vSphere DRS (load balancing) and vSphere HA fail to function on the affected host, often accompanied by "vSphere HA agent unreachable" or network connectivity alarms in vCenter.

Resolution

To resolve this issue, the affected host must be updated to match the ESXi version and build number of the other nodes in the cluster.

Verify the Version Mismatch

1. Log in to the vSphere Client (vCenter).

2. Select the healthy cluster nodes and note their Hypervisor version and Build number on the Summary tab.

3. Select the affected node and compare its version/build number. Confirm that it is running an older/newer release.

Additional Information

Here are some resources for upgrading vSphere ESXI 7.x to 8.x:

kb 390293 - Install or upgrade ESXi from 7.x to 8.x

kb 317899 - Update sequence for Vsphere 7.0 and its compatible VMware product

kb 315278 - vSphere 7 Upgrade Best Practices

kb 317896 - Important information before upgrading to vSphere 7.0

kb 312160 - vSphere ESXI Back-in-Time release upgrade restriction (upgrade matrix)