Owin provide startup class in web.config (no automatic startup discovery)

Simply remove this line of code in web.config file:

<add key="owin:AutomaticAppStartup" value="false" />

Your web.config file now must look like this:

<appSettings>
    <add key="owin:appStartup" value="MyNamespace.MyStartupClass" />
</appSettings>  

By adding just owin:appStartup key you don't need startup attribute.