Every now and then when using MDT Lite Touch to deploy Windows you may run into a yellow summary screen (warning screen) with the following warning message: Unable to create WebService class
Background
In the preceding example there were some other warnings as well, but you often find the Unable to create WebService class message event when there are no other warnings or errors. This error is typically caused when you are using the MDT Monitoring Service, and the client could not connect to the event service for whatever reason. For example, when waiting for a network connection. Theses warning messages are typically harmless but of course a bit annoying.
Fix
I normally don't recommend editing the default script, but if you want to have your summary screen look nice, simply comment out line 391 in the ZTIUtiliy.vbs script like below, and then update your deployment share (ZTIUtility.vbs is one of the files that gets injected into the boot image):
Note: Don't forget to replace any boot images in either WDS or iPXE when done with the update.
' oLogging.CreateEntry "Unable to create WebService class", LogTypeWarning