Telerik License Error CS0234 in Telerik UI for ASP.NET AJAX

Updated on Jul 24, 2026

Environment

Product	UI for ASP.NET AJAX
Version	2025 Q1 and newer

Description

I receive the error CS0234: The type or namespace name 'EvidenceAttributeAttribute' does not exist in the namespace 'Telerik.Licensing' (are you missing an assembly reference?) when working with the TelerikLicense.cs file in a project using Telerik UI for ASP.NET AJAX. This error occurs after installing the controls through the Telerik Control Panel.

Cause

Starting with version 2025 Q1, Telerik UI for ASP.NET AJAX requires activation using a License/Script Key. Additionally, the Telerik.Web.UI.dll assembly now depends on the Telerik.Licensing.Runtime.dll assembly, which is essential for proper licensing.

Solution

To resolve this issue, ensure the Telerik.Licensing.Runtime.dll assembly is properly included in your project. Follow these steps:

1. Verify that the Telerik.Licensing.Runtime.dll assembly is present in the project's BIN folder.

2. If the assembly is missing, add it to your project by performing one of the following:

   • Obtain the Telerik.Licensing.Runtime.dll assembly from the official Telerik Licensing NuGet package.
   • Download a manual installation from https://www.telerik.com/account/downloads/product-download?product=RCAJAX. locate the Telerik.Licensing.Runtime.dll file in the Bin462 folder and manually reference it in your project.

3. For web application projects, it is recommended to add the assembly via NuGet. Run the following command in the NuGet Package Manager Console:

   Install-Package Telerik.Licensing

4. Rebuild the project and ensure no errors appear.

5. If the issue persists, verify that the .csproj file includes a reference to Telerik.Licensing.Runtime.dll. Example:

   xml

   <Reference Include="Telerik.Licensing.Runtime">
       <HintPath>path-to-bin-folder\Telerik.Licensing.Runtime.dll</HintPath>
   </Reference>

6. Confirm that the correct version of the Telerik.Web.UI.dll and Telerik.Licensing.Runtime.dll assemblies are being used.

See Also

• Telerik UI for ASP.NET AJAX Licensing Documentation
• Telerik Licensing NuGet Package