I was luckily enough to attend an excellent session at VMworld ran by Eamon Ryan which covered the top 10 Virtualization Support Issues today. I found this particularly useful as many of them covered upgrading to vSphere 5.0
This is an hot add issue after a snapshot which can cause the VMX file to get corrupt on ESX 5.0. Luckily enough there is simply a patch to install which fixed the problem.
The is an issue with vmotion failing when enabling 3D graphics and hardware version 8 (vSphere 5.0) To fix this a manual edit of the VMX file is required which is list in the link.
vCenter server does not support the older version of converter and there is no upgrade to it. A work around is to simply install the stand a lone converter product.
If you manually uninstall the HA agent and then try to install it manually again it will fail. The simple fix is to use the GUI.
This is only HP related but ESX 5.0 can fail to see drives bigger than 2TB on HP P400 RAID controllers
The VirtualCentrer Server service fails to start with alarm errors after upgrading to vCenter Server 5.0.
After installing ESXi 5.0 and using software iSCSI errors the boot time can be excessively long. This is because it will try to poll all targets and if it fails it will try again 9 more times. The work around for this is to reduce the retry number.
Upgrading from ESXi 4.0 U2. Note this is version specific. You may get a purple screen of death when upgrading ESX and the vCenter. The quick fix is not to upgrade from 4.0 U2. Simply patch ESX up to the currently highest for U4 before upgrading to ESXi 5.0.
If you import the wrong bundle into VUM then VUM may report that it is unable to scan, stage or remediate ESXi5.0 hosts. Simply make sure you are using the correct bundle for VUM. Not Zips that end with “depot”.
There is some confusion about where the VMware HCL and product interoperability matrixes. It used to be in a PDF but now you will find it at. http://partnerweb.vmware.com/comp_guide2/sim/interop_matrix.php?
This KB is some useful info for upgrading with mainly video content.