ASP.NET IIS Web.config [Internal Server Error]

I had a problem with runAllManagedModulesForAllRequests, code 0x80070021 and http error 500.19 and managed to solve it

With command prompt launched as Admnistrator, go to : C:\Windows\Microsoft.NET\Framework64\v4.0.30319>

execute

aspnet_regiis -i

bingo!

Check this in the web.config and change overrideModeDefault from Deny to Allow.

<configSections>
  <sectionGroup name="system.webServer">
    <section name="handlers" overrideModeDefault="Deny" /> 
    <section name="modules" allowDefinition="MachineToApplication" overrideModeDefault="Deny" />

You can also manage sections on web server level in your IIS management console from "Feature Delegation".