Second calendar on an O365 Group? Mystery calendar

Occasional Contributor


We have some users with an Office 365 Group. Recently, they reported that not all of their appointments/meetings not always showing up on their calendars. However, upon further inspection, it looks like they have two calendars.

When I get to the Group's calendar the normal way (via the ribbon in Outlook), I see one calendar. However, it looks like they have tried to add the calendar to shared calendars by going to Shared Calendars>Add Calendars>From Address book. If you search for the O365 group name, and select that group from the address book, it pulls an entirely new calendar (with the same name as the Group). There are no overlapping events between the two, and I can display them alongside each other.

When I inspect the 'normal' calendar (the one I access via Groups), it seems normal. However, when I try to inspect the calendar under shared calendars I get an error, "Cannot display the folder properties. The folder may have been deleted or the server where the folder is stored may be unavailable. Cannot display folder properties. You don't have appropriate permission to perform this operation." The shared calendar instance also only displays free/busy info.

I am an Exchange Admin, and I cannot find another instance of the calendar in the Exchange Admin Center. I can of course see the O365 Group in Exchange.
Any ideas?

2 Replies
best response confirmed by Anna Ewart (Occasional Contributor)

Simply run the Get-MailboxFolderStatistics against the group mailbox and see the list of folders there, then depending on the results we will decide on action. You can also run a message trace for one of the "missing" events, the detailed trace should show you whether it was redirected somewhere.

Thank you for your response! Unfortunately neither of those suggestions got me very far. Get-MailboxFolderStatistics didn't give me anything unusual, and the calendar folder didn't seem to have a full listing of events from the 'mystery' calendar. I was unable to run a message trace on the group email address.


I just spoke with the user and they plan to just use an existing shared mailbox calendar. So I'm going to be deleting the O365 group in this case.

Really strange! I guess we can consider this resolved, though there was not really a technical solution/answer.