In this article you will learn about a Designer workflow with a Call HTTP Web Service action in SharePoint 2013.
When working on one of the workflow development tasks, it was required to have a web service call to fetch data from SharePoint. To do that I used a "Call HTTP web service" action but with that I was getting the following exception “Unable to de-serialize HTTP response content. Expected Content Type: 'application/json', 'text/plain' or 'text/html'”.After struggling with this issue, the solution I used thought to share the solution with the developer community.Solution: The reason for the issue is, by default response from SharePoint REST is in XML and the SharePoint designer workflow is not able to parse the XML and needs a JSON response. To resolve this issue we need to pass Accept and Content-Type as application/json;odata=verbose to request the headers. This way we will get a JSON response. To resolve this use the following procedure.