Potential impact of a guest OS mismatch and recommended actions for VM's running in vSphere environment.

Products

• VMware vSphere ESX 7.x
• VMware vSphere ESX 8.x
• VMware vSphere ESXi

Issue/Introduction

• VM deployed with a specific guest OS selected during its initial configuration.
• The operating system inside the VM was upgraded or changed, but the configured guest OS in the VM settings was not updated to reflect this change.

Environment

VMware vSphere 7.x
VMware vSphere 8.x

Cause

A mismatch occurs when the guest OS setting in the VM configuration does not reflect the actual OS installed and running inside the VM. This typically happens after an in-place OS upgrade or a manual change within the guest without corresponding updates in the VM's configuration.

VMware relies on the configured guest OS setting to:

• Determine the appropriate default virtual hardware and device types

• Optimize VMware Tools functionality

• Apply compatibility checks and resource handling

Resolution

To ensure compatibility and optimal performance, it is recommended to update the VM configuration to reflect the actual guest OS running inside the virtual machine.

Recommended Action:

1. Gracefully shut down the virtual machine.

2. Open the VM settings via the vSphere Client.

3. Update the Guest OS field to match the current operating system running inside the VM.

4. Save changes and power the VM back on.

Additional Information

Note:

• This change does not affect the guest OS itself.

• A mismatch may not result in immediate failures, but can lead to degraded performance, inaccurate reporting, or VMware Tools not functioning optimally.

• Updating the setting ensures the VM benefits from proper hardware compatibility and support alignment.