An ASP.NET setting has been detected that does not apply in Integrated managed pipeline mode.

i had

<configuration>
  <system.web>
    <httpModules >
      <add name="BlahModule" type="blahModule" />
    </httpModules>
  </system.web>
</configuration>

instead of


<configuration>
    <system.webServer>
      <handlers>
     </handlers>
       <modules>
<add name="BlahModule" type="blahModule" />
        </modules>
     </system.webServer>
</configuration>