I’m was busy modifying a pre-existing workflow template of mine, by adding an additional task. I decided that the task should not be contrained by any due dates, so I didn’t provide any Due Date Provider for my task. I was able to re-configure my workflow with the new task without any issues. However after submitting my record, my workflow history reflected that my task had been started, but no users were assigned. Debugging my workflow revealed that the Participant Provider was functioning correctly and returning the correct user, but yet my workitem was not being assigned. On further investigation the event log on the IIS server revealed the following message:
Workflow instance: 6f5ac316-52b3-48f0-b401-93af89889a21 was terminated for the following reason: Specified argument was out of the range of valid values. Parameter name: constraintDate.
Now I’m not sure what the real cause of the problem is, but after adding a Due Date Provider to my task and re-configuring accordingly the workitem was successfully assigned. Hopefully I will come to a conclusion as to why I am unable to leave the Due Date Provider property empty sometime in the future, but for the moment this is a successful work around for my issue.
Happy Daxing.
Dynamics AX Workflow Wanderings 
Hello Jonathan,
We are working on Dynamics AX 2009 in my company and we have a purchase order that failed due to bad configuration on the workflow version. I wonder if there is any way to change the version of workflow for a purchase order to a recent one?
Thanks in advance.
Hi Alfred.
The best way is to use the cancel functionality to stop the current workflow instance and then resubmit once it has successfully been cancelled. Alternately you may need to manually reset your purchase order status’ and delete the workitems associated with the PO.
Regards
Jonathan