Forum Discussion
changing working times on an existing Project file
I have a large MS Project that was prepared using the standard calendar, but that calendar uses different daily shift times than what we want to use. I created a new calendar with the correct shift (working) times, set the Project to use that new calendar, but the old calendar times are still being used for new tasks, and existing tasks still have the old calendar times. I even changed all the individual tasks to use the new calendar with no effect. How can I force an existing Project use the correct calendar?
1 Reply
Try this to force the new calendar to apply:
1. Update the Project Calendar
o Go to Project → Project Information → Calendar and select your new calendar.
2. Check Resource Calendars
o Open the Resource Sheet.
o For each resource, ensure their calendar is based on your new calendar (or update their working times to match).
3. Recalculate task schedules
o After changing calendars, force Project to recalc:
Select all tasks (Ctrl+A in Gantt view).
Use Task → Information → Advanced tab → Calendar and clear any custom task calendars.
Then press F9 (Calculate Project).
o This will reapply the new calendar’s working times.
4. If tasks still don’t shift
o Check if constraints (e.g., “Must Start On”) are locking them. Remove or loosen constraints.
o Verify “Scheduling ignores resource calendars” is not blocking changes.
