Unable to start upgrade of hosts due to the error - "Multiple-NSX managers per vCenter feature is enabled but NSX-T Data Center is installed on the following host(s)"

Products

• VMware vCenter Server
• VMware NSX
• VMware vSphere ESXi

Issue/Introduction

• You are proceeding with an upgrade of the hosts but the vLCM halts the upgrade as it has an issue with "NSX Multi" mode being enabled on the vCenter. 
• The following message is reported by the LCM:

"Multiple-NSX managers per vCenter feature is enabled but NSX-T Data Center is installed on the following host(s): <Host FQDN>, <Host FQDN>, <Host FQDN> Uninstall NSX-T Data Center from the hosts"

Environment

VMware vCenter Server

VMware ESXi 7.X

VMware NSX

Cause

• The message from the vLCM is being reported and blocked since Multi-NSX it is not compatible with vLCM. 
• In the Technical Documentation the following limitation is noted:
  
  "With Multi NSX enabled on a VMware vCenter, you cannot enable Kubernetes cluster or vLCM cluster to work on the same VMware vCenter."

Resolution

• Disable 'Multi-NSX' so vLCM can pass this check on the next run of the upgrade and proceed to the upgrade of the hosts.
• Before disabling 'Multi-NSX' ensure no additional NSX Manager clusters are installed and managing VIB's on a host in that vCenter.
• Use the following steps to disable 'Multi-NSX':
  1. In the NSX Manager UI Select System->Fabric->Compute Managers->Add Compute Manager.
  2. Select the compute manager from the list and click edit.
  3. Select No for 'Multi NSX' like the screenshot below and click save:

Additional Information

For more information on Multi-NSX refer to the Tech Docs.