# Located Assembly Manifest Definition Does Not Match the Assembly Reference Error

## Environment

<table>
	<tbody>
		<tr>
			<td>Product</td>
			<td>Progress® Telerik® UI for ASP.NET AJAX</td>
		</tr>
	</tbody>
</table>

## Description

When working with Telerik UI for ASP.NET AJAX, I get an error that the located assembly's manifest definition does not match the assembly reference.

## Error Message

`System.IO.FileLoadException: Could not load file or assembly 'Telerik.Web.UI, Version=xxxx.x.xxx.xx, Culture=neutral, PublicKeyToken=xxxxxxxxxxxxxxxx' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)`

## Solution

For more information on the cause and solution of this issue, refer to [the upgrading instructions](https://www.telerik.com/products/aspnet-ajax/documentation/upgrade-compatibility/upgrading-instructions/upgrading-a-trial-to-a-developer-license-or-to-a-newer-version) article.