I’m running a website on IIS8.5, but it gives me only a blank page and the following error in the IIS logs: status error 500 and sc-substatus 19

There is not much documentation on this error, the Microsoft website has a list with errors, with only the description: “Configuration data is invalid”. There is more detailed information here, but I didn’t get any Hresult codes.

After searching for clues, I finally found the solution: in IIS Manager, under the Server name → Feature delegation the IP Address and Domain Restrictions was set to readonly. This must be set to read/write in order to be able to get it working in the web.config. The same holds for the Handler Mappings in the web.config.