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 installin

Answer 1

Probably related question: .NET using wrong 2.0 machine.config instead of 4.0. I've experienced similar issue... And solution for me:

Not sure, that it's realy reason/solution, but last thing I've try it is (in IIS Manager):

1. Navigate to server in right panel (root node)
2. In the features list open "ISAPI and CGI Restrictions"
3. There is 2 items with descriptions ASP.NET v4.0.30319 with restrictions set to Deny
4. Set restrictions value to Allowed

This is last thing i've tried before issue is gone.

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

For me, changing the application pool .NET Framework version from v2.0 to v4.0 solved this issue.

Open IIS --> Select App Pools --> Select App Pool from list --> From context menu select Basic Settings... --> Change .NET Frame version to v4.0

Answer 4

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

Answer 5

c:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_regiis.exe -i

I tried this and it works good for me. Maybe helpful to someone.

Answer 6

Note down .netFramework version v4... (examplev4.0.030319) you have installed Edit your application pool to correct .NET Framework v4..

Good luck

-Satish