Unable to converge vSphere Environment using VUM to VCF 9.0 with Error: "Invalid cluster size present"

Products

• VMware vCenter Server

Issue/Introduction

When attempting to converge a vSphere environment to a VCF 9.0 environment using the VCF Installer the below error is displayed and the conversion cannot be completed:

Invalid cluster size present. VUM non-vSAN cluster has size 2 which is unsupported for CONVERT operation

Environment

VUM managed vSphere clusters with 2 hosts. 

vCenter Server 8.0

ESXi 8.0

VCF 9.0

Cause

When attempting to converge a vSphere environment with VCF 9.0, 3 is the minimum number of hosts in a VUM managed cluster. 

Resolution

Upgrade vCenter to 9.0: 

1. Upgrade vCenter Server from 8.0  to vCenter Server 9.0
2. Upgrade ESXi hosts to version 9.0
3. Convert clusters to vLCM image-based management
4. Re-initiate VCF 9.0 convergence using the VCF Installer

If you can not upgrade the vCenter/ESXi to 9.0 and are still experiencing this issue, please create a Broadcom support ticket and reference this KB.