You must install .NET Framework 4.5 before you can successfully install WebReports.
You normally install .NET Framework 4.5 immediately after installing SQL Server, and immediately before installing the WebReports installer. However, if you have previously installed .NET Framework 4.5 for any reason, you need to repair the .NET Framework 4.5 installation.
Even though you install .NET Framework 3.5.1 while adding Windows features, you must also install .NET Framework 4.5 for successful WebReports and Building Operation installation. For more information, see Windows Roles and Features .