The Type QueryableEntityCollectionView<T> Exists in Both Telerik.Windows.Controls.EntityFramework and Telerik.Windows.Controls.EntityFramework60 Error

Updated on Oct 1, 2025

Environment

Product Version	2020.2.617
Product	Telerik UI for WPF

Description

An error "The type QueryableEntityCollectionView exists in both Telerik.Windows.Controls.EntityFramework and Telerik.Windows.Controls.EntityFramework60" is shown when installing the Telerik.UI.for.Wpf nuget that contains all Telerik UI for WPF dlls.

Solution

This happens because the QueryableEntityCollectionView dll is defined in both the Telerik.Windows.Controls.EntityFramework and Telerik.Windows.Controls.EntityFramework60 dlls. To resolve this you will need to remove one of the two dlls (based on the EntityFramework version you are using - 5 or 6+). If you're using NuGet packages, you need to use separate nuget packages to avoid this error.