Question

When i am running the application,i got an error as follows:

Microsoft JScript runtime error:Sys.ArgumentTypeException:Object of type ‘Sys._Application’ cannot be converted to type ‘Sys._Application’.Parameter name:instance

Answer 1

This error can happen if your web.config is not properly configured to use Microsoft’s ASP.NET Ajax.

If you have VS2008, this settings are added automatically. In VS2005, if your ASP.NET project does not start out as Ajax, you need to add the settings manually.

Here’s an example:

<configuration>    <configSections>      <sectionGroup name='system.web.extensions' type='System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'>        <sectionGroup name='scripting' type='System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'>          <section name='scriptResourceHandler' type='System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' requirePermission='false' allowDefinition='MachineToApplication'/>          <sectionGroup name='webServices' type='System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'>            <section name='jsonSerialization' type='System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' requirePermission='false' allowDefinition='Everywhere'/>            <section name='profileService' type='System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' requirePermission='false' allowDefinition='MachineToApplication'/>            <section name='authenticationService' type='System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' requirePermission='false' allowDefinition='MachineToApplication'/>          </sectionGroup>        </sectionGroup>      </sectionGroup>    </configSections>    <system.web>      <pages>        <controls>          <add tagPrefix='asp' namespace='System.Web.UI' assembly='System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>        </controls>      </pages>      <compilation debug='true'>        <assemblies>          <add assembly='System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>          <add assembly='System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A'/>          <add assembly='System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089'/>        </assemblies>      </compilation>      <httpHandlers>        <remove verb='*' path='*.asmx'/>        <add verb='*' path='*.asmx' validate='false' type='System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>        <add verb='*' path='*_AppService.axd' validate='false' type='System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>        <add verb='GET,HEAD' path='ScriptResource.axd' type='System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' validate='false'/>      </httpHandlers>      <httpModules>        <add name='ScriptModule' type='System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>      </httpModules>    </system.web>    <system.web.extensions>      <scripting>        <webServices>          <!-- Uncomment this line to customize maxJsonLength and add a custom converter -->          <!--            <jsonSerialization maxJsonLength='500'>              <converters>                <add name='ConvertMe' type='Acme.SubAcme.ConvertMeTypeConverter'/>              </converters>            </jsonSerialization>          -->          <!-- Uncomment this line to enable the authentication service. Include requireSSL='true' if appropriate. -->          <!--            <authenticationService enabled='true' requireSSL = 'true|false'/>          -->          <!-- Uncomment these lines to enable the profile service. To allow profile properties to be retrieved               and modified in ASP.NET AJAX applications, you need to add each property name to the readAccessProperties and               writeAccessProperties attributes. -->          <!--            <profileService enabled='true'              readAccessProperties='propertyname1,propertyname2'              writeAccessProperties='propertyname1,propertyname2' />          -->        </webServices>        <!--          <scriptResourceHandler enableCompression='true' enableCaching='true' />        -->      </scripting>    </system.web.extensions>    <system.webServer>      <validation validateIntegratedModeConfiguration='false'/>      <modules>        <add name='ScriptModule' preCondition='integratedMode' type='System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>      </modules>      <handlers>        <remove name='WebServiceHandlerFactory-Integrated'/>        <add name='ScriptHandlerFactory' verb='*' path='*.asmx' preCondition='integratedMode' type='System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>        <add name='ScriptHandlerFactoryAppServices' verb='*' path='*_AppService.axd' preCondition='integratedMode' type='System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>        <add name='ScriptResource' preCondition='integratedMode' verb='GET,HEAD' path='ScriptResource.axd' type='System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'/>      </handlers>    </system.webServer>  </configuration>