Problema:

Inserendo nel web.config la voce  

<modules runAllManagedModulesForAllRequests=”true” />

si verifica l’errore  

This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault=”Deny”), or set explicitly by a location tag with overrideMode=”Deny” or the legacy allowOverride=”false”.

Soluzione:

Editare il file applicationHost.config presente nella cartella del server c:\windows\system32\inetsrv\config e cambiare la voce  

<section name=”modules” allowDefinition=”MachineToApplication” overrideModeDefault=”Deny” />

in

<section name=”modules” allowDefinition=”MachineToApplication” overrideModeDefault=”Allow” />