I am experience this error on of my hosts. I have other hosts that are working fine hanging off the same vcenter.
I can get to the http://<hostip>/mob and log in just fine.
I have tried polling directly and through vcenter, each producing the same error.
Does anyone know of anything else I can check? I'm not sure what URL it is referring to.
if you still face the problem it would be probably best to create a support ticket.
If you are familiar with sql, you check what is the service uri id of your particular host (run database manager, execute this query: select hostname,serviceuriid from vim_hosts). Find your ID and check if it's available in VIM_ServiceUris (select * from vim_serviceuris). Eventually you can fix the ID in the hosts table.