How to fix HA errors in VMware ESX Server?

1. Make sure all the hosts in the cluster are able to resolve each other by host name.

2. If they were not able to do so, check the DNS settings.

3. Best solution is to add all the hosts names and ip addresses into /etc/hosts file on all ESX servers in the cluster. Put the ESX server in maintenance mode before doing any changes.

4. Exit from the maintenance mode and try to reconfigure the HA on all the ESX hosts one by one, that's it your problem will be fixed.

NOTE : DO NOT FORGET TO PUT THE ESX SERVER IN MAINTANANCE MODE BEFORE CHANGING ANYTHING ON IT.