asp.net - The configuration section 'appSettings' cannot be read because it is missing a section declaration -

i clearing asp.net temporary internet files , accidentally deleted .net framework files (i have 3.0, 3.5, 4.0 , 4.5) neither visual studio 10 or visual studio 2012 opening. repaired installation of .net framework , able open vs again. though every web application buildable, when trying run any, error in web.config appsettings, though appsettings working before deleting incident, appears.

i don't know went wrong , how fix this.

iis error:

http error 500.19 - internal server error

the requested page cannot accessed because related configuration data page invalid.

error code

0x80070032

config error

the configuration section 'appsettings' cannot read because missing section declaration

the config file:

 <?xml version="1.0"?> <configuration>   <configsections>     <section name="cid.dal" type="cid.dal.bases.nettiersservicesection, cid.dal" allowdefinition="machinetoapplication" restartonexternalchanges="true"/>     <section name="enterpriselibrary.configurationsource" type="microsoft.practices.enterpriselibrary.common.configuration.configurationsourcesection, microsoft.practices.enterpriselibrary.common, version=4.1.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>     <sectiongroup name="applicationsettings" type="system.configuration.applicationsettingsgroup, system, version=2.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089">       <section name="cidportal.properties.settings" type="system.configuration.clientsettingssection, system, version=2.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089" requirepermission="false"/>       <section name="cidwebsite.properties.settings" type="system.configuration.clientsettingssection, system, version=2.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089" requirepermission="false"/>     </sectiongroup>     <sectiongroup name="system.web.extensions" type="system.web.configuration.systemwebextensionssectiongroup, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35">       <sectiongroup name="scripting" type="system.web.configuration.scriptingsectiongroup, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35">         <section name="scriptresourcehandler" type="system.web.configuration.scriptingscriptresourcehandlersection, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35" requirepermission="false" allowdefinition="machinetoapplication"/>         <sectiongroup name="webservices" type="system.web.configuration.scriptingwebservicessectiongroup, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35">           <section name="jsonserialization" type="system.web.configuration.scriptingjsonserializationsection, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35" requirepermission="false" allowdefinition="everywhere"/>           <section name="profileservice" type="system.web.configuration.scriptingprofileservicesection, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35" requirepermission="false" allowdefinition="machinetoapplication"/>           <section name="authenticationservice" type="system.web.configuration.scriptingauthenticationservicesection, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35" requirepermission="false" allowdefinition="machinetoapplication"/>           <section name="roleservice" type="system.web.configuration.scriptingroleservicesection, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35" requirepermission="false" allowdefinition="machinetoapplication"/>         </sectiongroup>       </sectiongroup>     </sectiongroup>   </configsections>   <appsettings>     <add key="bll.cruwebreference" value=""/>     <add key="bll.crulogopath" value=""/>     <add key="bll.kbixmlpath" value="d:\app\kbi\xml\{0}\"/>     <add key="bll.cruwebreference_staging" value=""/>     <add key="bll.kbixmlpath_imc" value="d:\app\kbi\xml\{0}\"/>     <add key="bll.kbixmlpath_stp" value="d:\app\kbi\xml\{0}\"/>     <add key="bll.kbiwslink" value=""/>     <add key="bll.kbiwshmclink" value=""/>   </appsettings>   <connectionstrings>     <add name="cid.dal.connectionstring" connectionstring="password=;persist security info=true;user id=;initial catalog=;data source="/>     <add name="cid_oldconnectionstring" connectionstring="data source=;initial catalog=;integrated security=true" providername="system.data.sqlclient"/>   </connectionstrings>   <cid.dal defaultprovider="sqlnettiersprovider">     <providers>       <add name="sqlnettiersprovider" type="cid.dal.sqlclient.sqlnettiersprovider, cid.dal.sqlclient" connectionstringname="cid.dal.connectionstring" providerinvariantname="system.data.sqlclient" entityfactorytype="cid.dto.entityfactory" useentityfactory="true" enableentitytracking="true" enablemethodauthorization="false" usestoredprocedure="true" defaultcommandtimeout="30"/>     </providers>   </cid.dal>   <system.web>     <compilation debug="true">       <assemblies>         <add assembly="system.core, version=3.5.0.0, culture=neutral, publickeytoken=b77a5c561934e089"/>         <add assembly="system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>         <add assembly="system.xml.linq, version=3.5.0.0, culture=neutral, publickeytoken=b77a5c561934e089"/>         <add assembly="system.data.datasetextensions, version=3.5.0.0, culture=neutral, publickeytoken=b77a5c561934e089"/>       </assemblies>     </compilation>     <authentication mode="windows"/>     <pages>       <controls>         <add tagprefix="asp" namespace="system.web.ui" assembly="system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>         <add tagprefix="asp" namespace="system.web.ui.webcontrols" assembly="system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>       </controls>     </pages>     <httphandlers>       <remove verb="*" path="*.asmx"/>       <add verb="*" path="*.asmx" validate="false" type="system.web.script.services.scripthandlerfactory, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>       <add verb="*" path="*_appservice.axd" validate="false" type="system.web.script.services.scripthandlerfactory, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>       <add verb="get,head" path="scriptresource.axd" validate="false" type="system.web.handlers.scriptresourcehandler, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>     </httphandlers>     <httpmodules>       <add name="scriptmodule" type="system.web.handlers.scriptmodule, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>     </httpmodules>   </system.web>   <startup>     <supportedruntime version="v2.0.50727"/>   </startup>   <system.codedom>       <compilers>         <compiler language="c#;cs;csharp" extension=".cs" type="microsoft.csharp.csharpcodeprovider, system, version=2.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089" warninglevel="4">           <provideroption name="compilerversion" value="v3.5"/>           <provideroption name="warnaserror" value="false"/>       </compiler>     </compilers>   </system.codedom>   <system.webserver>       <validation validateintegratedmodeconfiguration="false"/>     <modules>       <remove name="scriptmodule"/>       <add name="scriptmodule" precondition="managedhandler" type="system.web.handlers.scriptmodule, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>     </modules>     <handlers>       <remove name="webservicehandlerfactory-integrated"/>       <remove name="scripthandlerfactory"/>       <remove name="scripthandlerfactoryappservices"/>       <remove name="scriptresource"/>       <add name="scripthandlerfactory" verb="*" path="*.asmx" precondition="integratedmode" type="system.web.script.services.scripthandlerfactory, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>       <add name="scripthandlerfactoryappservices" verb="*" path="*_appservice.axd" precondition="integratedmode" type="system.web.script.services.scripthandlerfactory, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>       <add name="scriptresource" verb="get,head" path="scriptresource.axd" precondition="integratedmode" type="system.web.handlers.scriptresourcehandler, system.web.extensions, version=3.5.0.0, culture=neutral, publickeytoken=31bf3856ad364e35"/>     </handlers>   </system.webserver>   <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> </configuration> 

i've had issue few times, first time when .net had became "de-registered" iis

c:\windows\microsoft.net\framework64\v4.0.30319\aspnet_regiis.exe -i 

fixed (or substitute .net path if not using 64 bit machine)

the other thing caused when iis application pool set .net 2.0 instead of .net 4 though .net installed. opened app pool in iis manager , switched , worked.