VMware Update Manager cannot remediate ESX host

What

when you do the ESX/ESXi host remediation using VMware Update Manager fails;

 

Error Message / Symptom

Cannot remediate host "hostname" because it is a part of a HA admission control enabled cluster.

 

Solution / Fix

temporary disable strict admission control: 

Right-click the cluster and click Edit Settings.

Under Cluster Features, click VMware HA.

Under Admission Control, select Disable: Power on VMs that violate availability constraints.

Click OK.  

OR

temporary disable VMware HA:

Right-click the cluster and click Edit Settings.

Under Cluster Features, select Turn off VMware HA.

Click OK.

If you do not want to disable strict admission control or HA at the cluster level, you can
 

1. Create a new Test Cluster in the Data centre
2. Move the ESX host being remediated into the new Cluster
3. Remediate the host

If the remediation completes successfully, the ESX host can now be moved back into the original HA cluster.