本来次项目发布后运行正常，客户说部署在他们的服务器上，就出现了下面的错误？
server error in '/' Application
Description:An error occurred during the proceing 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=2.0.0.0,Culture=neutral,publickeytoken = 31bf3856ad364e35' or one of its dependencies. This system cannot find the file specified.(d:\web\website\web.config line 65)
Source Error:
</httpHandlers>
<httpModules>
<add name ="ScriptModule" type="system.web.handlers.scriptModule,System.web.Extension,version=2.0.0.0,Culture=neutral,publickeyToken=31bf3856ad364e35"/>
</httpModules>
</system.web>