The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration

Question

I am getting error (The configuration section system.web.extensions cannot be read because it is missing a section declaration) while installing my Web Application in Server 2008 32 bit machine with .NET Framework 4.0. but it works well in 2008 r2 64 bit machine.

This is my webconfig file info

<configuration>
<runtime>
    <assemblyBinding appliesTo="v2.0.50727" xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="3.5.0.0"/>
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <system.web.extensions>
    <scripting>
      <webServices>
        <jsonSerialization maxJsonLength="2147483647"/>
      </webServices>
    </scripting>
  </system.web.extensions>
</configuration>

Any idea to get rid of this error?

Note: I have checked all the related entries in Stack over flow but nothing was useful for me

Answer 1

Try changing the application pool run time from .net 2.0 to .net 4.0

Answer 2

The issue resolved for me after adding the following configuration setting in my webconfig file

<configSections>
    <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
      <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
        <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication"/>
        <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
          <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="Everywhere"/>
        </sectionGroup>
      </sectionGroup>
    </sectionGroup>
  </configSections>

We can refer this article for more info: http://www.morgantechspace.com/2013/11/The-configuration-section-system-web-extensions-cannot-be-read-because-it-is-missing-a-section-declaration.html

Answer 3

I also had the same problem after upgrading my OS from Windows Server 2003 to Windows Server 2008 R2 , I just changed the application pool settings to .NetFramework 4.0.0 and also changed the classic to Integrated mode ... my problems solved ..