Since .NET Core is a new implementation of the .NET environment, there is no binary compatibility with existing .NET assemblies. There are APIs defined in the full .NET Framework that are not compatible with .NET Core. This is true for Microsoft's ReportViewer.As described in the previous section, this is the component used to render report . This component depends on the ASP.NET WebForms infrastructure. Having a direct dependency in this control implies that the modernized application cannot take advantage of the .NET Core features. This is the reason of having an external service that take care of rendering the report. This service is called ReportWatcher.