We sometime may overlook the very basic thing and because of this, it can caused you some hick up to your production environment. Same goes to me when I tried to reconfigure one of the ESXi host and suddenly a long error came out from nowhere “Cannot synchronize host dc2esx02. A general system occurred. Unexpected exception reading HTTP bla bla bla….”. To cut the story shot, what you have to do normally is to follow exactly what has been mentioned in this KB. I’ve done successfully a few cases before but luckily for this case, I don’t have to. Since the snapshots was back dated in Nov last year. I just need to delete all unused snapshot, modify some parameters in .vmsd file to “False”. Then, I’m able to reconfigured the HA or power on the VM without problem anymore.