I upgraded one of my esxi hosts from 5.5 U2 to U3 and after the host upgrade it disconnected from vcenter which is 5.5 U3 as well. The error message states:
Datastore conflicts with an existing datastore in the datacenter that has the same URL but is backed by different physical storage.
After researching this it appears that this is a bug in 5.5. I have reviewed the following KB:
The vml and naa info is the same between the upgraded host and a current host. It states to remove the host from vcenter and then re-add the host, but the option to remove the host is grayed out. I can hit the connect button which produces the error above and then asks for credentials. I have not followed through with entering the credentials since I am not sure it is safe to go ahead with this step. Anyone else experience this?