Sending HTTP request from Scheduler

I need to send http requests from the Scheduler, but end up with the following error.

Origam.HttpTools [(null)] <(null)> - Request could not be authenticated because serviceProvider is null. 
This is expected if you send Http requests from the Architect.

This was already discussed in Architect: cannot call HttpService.SendRequest from WF Execution in Architect and Scheduler: WF with http request step ends with error, but only an error message was added.

How can I make it work?