Hi - I have a ESXi 4.1 host that I've tried to upgrade to ESXi 5.5 today, The upgrade went through successfully (no errors), but when the host was rebooted (after removing the image disk) it came up as ESXi 4.1! Some relevant history: - I tried upgrading this same host from ESXi 4.1 to ESXi 5.1 almost a year ago and I ran into the same issue. I tried a few times then, and ultimately gave up on it. I figured with 5.5 vmware might have resolved this upgrade issue, so it was worth a try. No such luck. Another point worth mentioning is that during my upgrade attempt today to 5.5, the installer detects the existing install but interestingly reports it as 5.1 even though vCenter and the server Console report the host as being on 4.1. This makes sense because my attempt to upgrade to 5.1 a year ago was successful as per the install program.
I though this was maybe a license issue. So I tried applying a ESXi 5 license, but it won't take it as it wants a 4.x license.
Server: Dell PowerEdge R710. Fully operational - no issues, other than the fact that I cannot upgrade it. Any help will be much appreciated.