The VMware Knowledge Base provides support solutions, error messages and troubleshooting guides
Unable to Power On a Virtual Machine After Virtual Hardware Upgrade if the Virtual Machine Has Additional Append/Undoable Mode Disk on Different Datastores (1003138)
If a virtual machine has more than one hard disk that reside on different datastores on an ESX Server 2.5.x host, then after an ESX Server upgrade to version 3.5, followed by a VMFS file system and virtual hardware upgrade, powering on the virtual machine fails with the following error message:
File was not found.
If the virtual hardware is not upgraded, the virtual machine can be powered on.
Request a Product Feature
To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.