If I try to upgrade my ESXi 5 server which is in maintenance mode, I get
C:\Program Files\VMware\VMware vSphere CLI>vihostupdate.pl -server 10.51.80.186
-username root -install -bundle C:\Documents and Settings\wdey\Desktop\scsi-fnic
-1.5.0.8-1OEM.500.0.0.472560.x86_64
Enter password:
This operation is NOT supported on 5.0.0 platform.
C:\Program Files\VMware\VMware vSphere CLI>