Client app installed via signed msi package and this error is seen in a very few instances.
Full error description:
 FATAL - EXCEPTION: Could not load file or assembly 'System.ServiceModel.Web, Version=126.96.36.199, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies.
This is .NET related error. Please reinstall .NET and restart the PC. It will then work.