While deploying a virtual machine from template I received an error when guest customization was running:
Windows could not parse or process the unattend answer file for pass [specialize]. The settings specified in the answer file cannot be applied. The error was detected while processing settings for components [Microsoft-Windows-Shell-Setup].
Per VMware KB 2008221 a ‘wrong product key‘ could cause this. Coincidentally I created and used a brand new Guest Customization for this deployment. Turned out I used a Server 2012 Datacenter KMS key instead of the Server 2012 R2 Datacenter KMS key (Microsoft KMS Keys). I deleted the VM and redeployed after correcting the Guest Customization thus solving the problem!