Thanks to the guys at v-front.de/2013/09/how-to-update-your-standalone-host-to.html
Do not upgrade the virtual hardware of your VMs!
If you try to upgrade the virtual hardware of your VMs to the new revision 10 after you have updated the host to ESXi 5.5 then the following warning will be displayed by the vSphere Client:
“If you upgrade the virtual hardware to this level, use the vSphere Web Client for managing these VMs.”
– Think twice here! Read the rest of this entry »