In this article I will explain how to solve the following error occurring when using ASP.Net AJAX Control Toolkit in Visual Studio project.
Could not load file or assembly 'AjaxMin, Version=4.97.4951.28478, Culture=neutral, PublicKeyToken=21ef50ce11b5d80f' or one of its dependencies. The system cannot find the file specified.
Exception Details: System.IO.FileNotFoundException: Could not load file or assembly 'AjaxMin, Version=4.97.4951.28478, Culture=neutral, PublicKeyToken=21ef50ce11b5d80f' or one of its dependencies. The system cannot find the file specified.
 
Error
Could not load file or assembly 'AjaxMin, Version=4.97.4951.28478, Culture=neutral, PublicKeyToken=21ef50ce11b5d80f' or one of its dependencies. The system cannot find the file specified.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IO.FileNotFoundException: Could not load file or assembly 'AjaxMin, Version=4.97.4951.28478, Culture=neutral, PublicKeyToken=21ef50ce11b5d80f' or one of its dependencies. The system cannot find the file specified.
 
 
Solution
In order to solve this error you need to follow the following steps.
 
1. Download the latest AJAX Control using the download link below.
     Download AJAX Control Toolkit
2. Extract the downloaded Zip file and look for AjaxMin.dll in the folder.
Could not load file or assembly 'AjaxMin. The system cannot find the file specified
3. Now copy this DLL in the BIN folder of your project and add its reference as shown below.
Could not load file or assembly 'AjaxMin. The system cannot find the file specified
4. Now run the project and you will not receive the error again.