Organizing meetings and social gatherings can be tedious with everyone’s schedule varying almost all the time. You can try to create a poll, ask people in group chats, or risk scheduling a fixed date without knowing who may be available.
Another way is to sync or share your calendar to a group of people and everyone can see which dates are convenient for all. Microsoft 365 allows its users to share their calendars with other users and groups even outside their organization. All they have to do is set the sharing permissions.
Unfortunately, some people are blocked by the syncing error message, “You don’t have permission to share your calendar with username.” Now this changes things especially if you are used to the hassle-free procedure of simply sharing your calendar.

So, how do you fix this issue? Let’s find out.
Possible Methods to Fix User or Group Calendar Permission Problem on Microsoft 365

There are different possible reasons why you may encounter the problem with your calendar sharing or group syncing on Microsoft 365. But, you can start fixing it by checking your Settings. Make sure that you have set the right permission parameters on how you want the sharing to be.
Verify All Users are Active and Not Blocked
If one user is disabled or no longer active, it may be the reason why the error appears. You have to check if all the users to whom you want to share the calendar are all active users. If there is at least one who isn’t, remove that user and try resharing.
You can check each user by running:
Get-MailboxFolderPermission -Identity user@domain.com:\Calendar. To remove the user, run the following in the PowerShell: Remove-MailboxFolderPermission.
Check and Delete Duplicate Calendar Shortcut in Outlook
To do so, access your user’s Calendars in both Outlook for Web and Microsoft Outlook. You may want to verify if you can see the Calendar items in the Mu Calendars and the Shared or People’s Calendars. If so, remove the Calendar item under the Shared or People’s Calendars.
If the duplicate does not appear on the Shared Calendar but on another list, you also need to delete the duplicate.
Try Sharing Calendars to Public Folders
Add your shared calendar to Public Folders. Users can simply add the calendar to Favourites to access it via the Calendar icon.
Wrapping Up!
It can be frustrating to see issues in processes that help you become more productive. Hope one of the solutions above resolves the calendar error in your Microsoft 365!