Cluster Agent VM cannot be powered on due to insufficient resources on cluster ##### (vCLS)

Products

• VMware vCenter Server

Issue/Introduction

Every minute, vCenter attempts to power on vCLS VM and it fails with an error showing insufficient resources on the cluster, despite cluster having plenty of resources. This issue was observed on a single host cluster.

From vmkernel.log:

2025-09-16T15:18:07.815Z cpu8:6170714)WARNING: Swap: 3683:Failed to create swap file '/vmfs/volumes/######-######-###-########/vCLS-######-###-###-###-########/vmx-vCLS-#####-###-###-###-######-######-#.vswp' 

From hostd.log:

2025-09-16T19:01:37.875Z info hostd[2098814] [Originator@6876 sub=vm] /vmfs/volumes/######-######-###-########/vCLS-vCLS-######-###-###-###-########/vCLS-vCLS-######-###-###-###-########.vmx: VMX exited: '-22 Initial VMX memory reservation failed.

Environment

vCenter 7.x

Cause

vCLS needs to be reset due to a vCenter restore.

 

Resolution

Place the cluster into retreat mode, and remove from retreat mode to regenerate vCLS VM.

Disable vCLS on a Cluster via Retreat Mode