There are errors during the remediation operation

"There are errors during the remediation operation" . I stared blankly at the screen. Why was this happening?

I was trying to update an older vSphere 4.0 setup with update manager. The server was already in maintenance mode, but after clicking "Remediate" the error message came up almost immediately. A retry did not help. Quick googling came up with the following:

http://www.vmware.com/support/vsphere4/doc/vsp_vum_40_rel_notes.html

Host Patch and Upgrade Remediation Might Fail
Host patch and upgrade remediation might fail with the message There are errors during the remediation operation if an inaccessible virtual machine exists on the host. The reason for this failure might be that the virtual machine files reside on a disconnected network storage.
Workaround: Connect the disconnected network storage or remove the inaccessible virtual machine from the vSphere inventory.


I checked the host, and indeed there was an inaccessible VM! It was a no longer used one, so I removed it from the inventory, and updating went fine after that.

Where would we be without Google, right? ;-)