Greetings!
I have three ESXi servers version 4.0 which are running under free license. Recently I am trying to upgrade it to version 5.1 and 5.5 but failed. It said "Operation failed" and seems there' some problem on my VMFS volume. I tried it on both 3 servers but all failed with the same error. I am wonder if there's any way to upgrade it directly from 4.0 to 5.5 as it seems impossible to do so. I have been searching on Google and VMWARE but no luck on this. Appreciate if you guys can provide some hints for this issue. Thank you.
Wesley.