While creating a SharePoint 2013 Workflow in SharePoint Designer 2013, for a simple task approval, I found the following 404 error on workflow execution:
After doing some research and reading this error closely, which shows a bit about “ExpandGroupsToPrincipals” in error message, I made following change in to the task Form of this workflow:
I unchecked “Assign a task to each member within groups” because this task was assigned to a single User not any Group. The error suggested that SharePoint was trying to expand this resource, which is a User, not a Group and throwing this Exception
Published this workflow after this change and all worked as expected.