I've got a problem with users. After importing PST files to Exchange Online accounts, they have a problem with calendars. whenever they want to modify an item, that has been created on old system, it says, that they don't have required rights to manage this item (as they didn't create it). using set-mailboxfolderpermission to modify permissions to calendar folder didn't do the trick (unless i have to grant those to Anonymous user?). the import was done from my admin-account (if that is important)
After importing data from PST to Exchange Online account, users can’t modify items imported to calendar
exchangeimportmigration
Best Answer
This is by design. From Microsoft:
So in a nutshell, the new mailbox/user isn't the "organizer" of the meeting and therefore can't modify it. The only solution is to recreate the items. I worked with Microsoft support on this very issue several months ago.