Making changes in the timephased portion of the view causes a conflict with task constraints
The task already has a constraint applied to it. At some earlier time, a task constraint was applied to this task so that it would start or finish on or before a specific date. You have made a change to the timephased portion of the view that conflicts with this constraint. To keep the timephased edit, the task constraint needs to change.
Note: Go to Change the timescale in a Project view or Set a task start or finish date (constraint) for a task for additional information.
Using the Planning Wizard, you can:
Keep the timephased edit and change the constraint.
Microsoft Project will keep the edits you made to the timephased portion of the view and change the constraint that was previously placed on the task.
Cancel the timephased edit and do not change the constraint.
Project will remove the timephased edit you made and will not change the task constraint.
If you don't want the Planning Wizard to display this information again, select the Don't tell me about this again check box.