Fix for Deleting Enterprise Calendars in Project Online when all other suggestions do Not work

Copper Contributor

I cannot delete Project Online Enterprise Calendars no matter what. I've tried all your suggestions, including removing it from the projects using them but no projects the calendars both at the project and task level. I tried the regular Delete under Enterprise Calendars but that says almost all projects are using all the enterprise calendars and not just the one I am trying to delete. I search for which project has a calendar/project listed and changed it to another calendar hoping this would work, of course not, it did not. I don't understand why when I try to delete only one of the many calendars, the message shows that all projects are using them all.  I checked the top 5 which did not have any. What is the fix for this?


4 Replies

Hello @Noreen1590 

Once the projects and any tasks have been updated, be sure to publish the projects, not just Save. What about resources, are any resources using the calendar/s? 

The only one that I could find out of ~1,000 projects had the calendar I wanted to removed but we want to remove about 20 of them.  The project had it at the task level, of course, I saved and "Published" it. Made no difference, still could not delete the calendar. Maybe there are several projects that are "actually" using them.  When I try to delete it the message that gets displayed lists projects that are using the starting with "A" and it is wrong, because they are not using that calendar.  This must be a bug with Project Online. If there a patch for this?

Hello @Noreen1590 ,

I've not seen this issue before so if you think there is a bug here, best to open a support ticket with Microsoft via your Microsoft 365 tenant, they will be able to investigate the logs and provide you details.


I hope you get it sorted.


Are you using baselines? If so, the calendar may be tied to a baseline, which is why you can't see it? I haven't testing this, so it's just a thought and may not work that way.

When I have issues like this I connect via Power BI and create custom queries as there are a lot of fields that are not visible through the UI.