Such an error is observed when the ASP.NET Web Forms site or application references an assembly which is built against a newer .NET version than the .NET configuration of the current project.
For example, if your project targets .NET 2.0 or 3.5, you will get this error because the Telerik assemblies that are referenced are built against .NET 4.0 (2018.1.117.40 -
the last two digits represent the .NET version
When you install the controls you will see three Bin folders - Bin35, Bin40 and Bin45 so you need to take the assemblies from the respective one, according to your project's .NET target. Please make sure that the assembly is correct for the target framework and then you should not encounter this error.
Get quickly onboarded and successful
with your Telerik and/or Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.