I’ve installed vSphere 4.1 many times since it was released last July, but last week I ran across an issue I’ve not seen before. I was helping a customer upgrade to vSphere 4.1 from version 4.0, and moving from ESX to ESXi at the same time, making it necessary to completely rebuild the hosts.

The unusual thing was that after we migrated the VM’s to the ESXi 4.1 hosts we could not upgrade VMware tools in the guests using any of the manual or automated methods, including VMware Update Manager.

Researching the issue online produced nothing better than a suggestion to download the VMware tools .iso from VMware’s web site, mount it to each VM and perform a manual tools upgrade. While this does work, it's a labor-intensive solution.

We opened a VMware support case and learned that this is a known issue. Sure enough, just a few days later VMware released a <a href="http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&amp;cmd=displayKC&amp;externalId=1027753">set of vSphere 4.1 patches</a>, one of which resolved our issue. We applied the updates and confirmed that our issue was resolved.

A link to the specific VMware KB article that resolved our issue can be found <a href="http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&amp;cmd=displayKC&amp;externalId=1027028">here</a>.