This error can occur if VMware tools is not installed on the template. 
     When i add new computer with new type instant provision sysprep customization, i get this error in quest managment console: Linked clone failed UploadVmFile UploadFile failed! WebException An exception occurred during a WebClient request. - IOException Unable to write data to the transport connection An established connection was aborted by the software in your host machine. - SocketException An established connection was aborted by the software in your host machine UploadVmFile UploadFile failed! WebException An exception occurred during a WebClient request. - IOException Unable to write data to the transport connection An established connection was aborted by the software in your host machine. - SocketException An established connection was aborted by the software in your host machine - Call Stacks - at VmLinkedClone.VmLinkedCloneService.CloneVmLinked String vmInvPath, String strSnapshotMor, String strNewVmName, String strSysprep, ManagedObjectReference morFolder, ManagedObjectReference morResPool, ManagedObjectReference morHost, String strDatastoreName, Boolean bQuickPrep, String....  When i use direct sysprep customization computer add without error.  I am use vworkspace 7.5 and Vmware Vshpere Vcenter server 4.1. HELP PLEASE! 
ERROR INSTANT PROVISIONING