Error: vSphere HA virtual machine failover failed alert remains active on powered-on VMs

Products

• VMware vCenter Server

Issue/Introduction

In the vCenter Server UI, multiple virtual machines may continuously display the following alert, even when the virtual machines are currently in a powered-on state:

vSphere HA virtual machine failover failed: Insufficient resources to fail over this virtual machine. vSphere HA will retry the fail over when enough resources are available. Reason: The host does not have sufficient resources to power on the virtual machine

Environment

• VMware vSphere (vCenter Server) 8.0.x
• vSphere HA

Cause

This issue occurs when the vSphere HA Admission Control feature retains stale alerts regarding insufficient failover resources. The cluster has sufficient resources to satisfy the Admission Control policy, but the alerts remain stuck in an active state incorrectly.

Resolution

To clear the stale alerts, force a recalculation of the cluster's current failover capacity by temporarily disabling and re-enabling Admission Control.

1. Log in to the vSphere Client.
2. Select the affected cluster in the inventory.
3. Navigate to Configure > vSphere Availability > Admission Control.
4. Temporarily set Admission Control to Disabled.
5. Reset all related alarms in vCenter to green.
6. Wait a few minutes for the environment to update.
7. Re-enable the Admission Control feature.

Additional Information

If the alerts return after performing these steps, the cluster is experiencing an actual resource constraint rather than a stale alert. In such cases, you must increase cluster resources, reduce VM reservations, or adjust the HA failover capacity. Refer to the following related knowledge base articles for troubleshooting actual HA resource constraints:

• KB 421814
• KB 396016
• KB 395334