Could not load file or assembly System.Web.Extensions

Posted By  dotnetfish On 11 Sep 2010 10:09:46
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Facing issue when my team member try to upload compiled source code from her development machine to new production server.The error is like following

Server Error in '/' Application.

Configuration Error

Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Could not load file or assembly 'System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

Source Error:

<add type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" name="ScriptModule">


  1. Copy AjaxControlToolkit.dll and AjaxControlToolkit.pdb version 1.0.61025.0 from my development machine to my ASP.NET App bin folder. (i install my AjaxControlToolkit in C:\Program Files\Microsoft ASP.NET\ASP.NET 2.0 AJAX Extensions\AjaxControlToolkit)
  2. Copy System.Web.Extensions.dll (C:\WINDOWS\assembly\GAC_MSIL\System.Web.Extensions) and System.Web.Extensions.Design.dll (C:\WINDOWS\assembly\GAC_MSIL\System.Web.Extensions.Design) from my development machine to my ASP.NET App bin folder.

Note:I have assume you also installed C drive, if not please check assembly location according your location.

The problem solved.hope this is save your time.

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