​I recently got assigned a simple SharePoint Workflow Task to be the first assignee to edit a Word doc. On clicking “Open this task” in Outlook/Word 2013, i’d get the following error:
Element ‘{http://www.w3.org/1999/xhtml}div’ is unexpected  according to  content model of parent element ‘{http://schemas.microsoft.com/office/infopath/2009/WSSList/dataFields}Body’

6-24-2013 8-48-42 AM

The immediate workaround is to check for any Rich Text fields in the SharePoint 2010 Task List or the associated task list for the workflow, and change them to Plain text instead.  In this case, the request field is associated with the Description field (Body is its internal name) of the task list. The field is a Note field (Multiple lines of text) and the infopath form expects it as a plain text.

6-24-2013 9-06-12 AM
Edit the Workflow again and re-save, and your end-user Workflow Task form should now open as expected:
6-24-2013 8-51-43 AM
Now – this being the year 2013, I get a little bummed out when we are not allowed to use Rich Text in fields. Checking into why this seemingly standard functionality would not be available in such a form, I spent a good deal of time with no apparent answer. I do know that Rich Text get’s unceremoniously kicked out of the party in various points of SharePoint (as with many other frameworks/CMS’s) due to the potential for XSS injection etc.- perhaps it’s just unsupported but I can’t find the official word on this.

If anyone knows how to wire up the Rich Text or Enhanced Rich Text fields to such a form, or why SharePoint 2013 seems to create Workflow Task lists with this incompatible field type set as default, please let me know!