SharePoint 2013 provides a new and improved SharePoint Designer action the Start a Task Process.
To learn more about it, just follow the excellent youtube video authored by SharePoint MVP Laura Rogers.
I’ve recently tried this activity and one of the issue I’ve faced is that when you assign this task process to a (SharePoint) group of people, the workflow get suspended or cancelled (with an error).
For instance, I’ve tested the following very basic workflow on my Office 365 preview site collection :
In my specific case Approvers is a SharePoint group containing the following users :
When I start my workflow as a site collection admin everything works well, but when a simple contributor (member) starts the workflow, he get the following error :
TYpe this request( _vti_bin/client.svc/Web/SiteGroups/GetById(12)/Users) in the browser returned this :
This is clearly a permission issue; therfore the best way to fix it is to use the new App Step provided in SharePoint Designer 2013
Basically the App Step is a great way to provide elevation of privilege in SharePoint 2013 workflows (at least in SPD 2013).
Even if a workflow is not an SharePoint App, it can behave like an app (and can be part of an app)
To provide more privilege to your workflow, go to your site settings and select site app permissions :
All workflows are associated with the (virtual) app named workflow; select the appid (between the second | and the @)
Copy this string on the clipboard, and invoke the page appinv.aspx :
The following form will show up :
Past your app Id in the app id textbox and click on the Lookup button:
Now in the App permission textbox, provide the permission you need For instance if you want the workflow step to have full control on the site collection, just provide this :
AppPermissionRequest Scope="http://sharepoint/content/sitecollection" Right="FullControl" />
Click Create and trust the workflow:
Now, go back to SharePoint Designer 2013, edit your workflow and you will notice that the App Step action is now available in the ribbon :
Reorganize your workflow by moving the Start a task process into an App Step :
Publish your workflow and test it with a Contributor and it should work now.