drtweakllc

Figured it out, there are many updates that require .NET Framework 4.5. You can slipstream it into your disc, the download link is here .NET Framework 4.5 and if you are using WinToolkit 1.5.3.12 add it under "add-ons". Once done everything works fine and the error is gone. maxXPsoft, thank you for your input.

I'm having the exact same issue, I have made about 10-15 setup USB drives and cannot narrow down the update causing the issue. Does anyone have a list of know updates that can cause issues when slipstreaming?