If you are getting below error on workflow .
Stopped (error): X++ Exception: Could not find user at SysWorkflowDueDateProvider-resolve SysWorkflowDueDateProvider-resolveDueDate
Then you need to check following things.
1. Check workflow configuration is user assigned for workflow approval elements .
2. Check user relation form if there is not employee assigned then you need to assign employee on user relation form.
Stopped (error): X++ Exception: Could not find user at SysWorkflowDueDateProvider-resolve SysWorkflowDueDateProvider-resolveDueDate
Then you need to check following things.
1. Check workflow configuration is user assigned for workflow approval elements .
2. Check user relation form if there is not employee assigned then you need to assign employee on user relation form.