Exchange Online: Calendar Permissions – “Some Permissions cannot be displayed”

I needed remove few disabled users from the permission set in the Calendar. I got this error: “The security principal specified is already on the permission set”. To fix this error, I was using my other blog post: https://anandthearchitect.com/2018/06/29/get-mailboxfolderpermission-the-security-principal-specified-is-already-on-the-permission-set/.

Here is the wrinke. If you have Full Access permission to a mailbox, when you open the Calendar Properties dialog box and select Permissions in Outlook, you will see a message Some permissions cannot be displayed.

Fortunately This is documented in https://support.microsoft.com/en-us/office/user-experience-changes-for-sharing-a-calendar-in-outlook-5978620a-fe6c-422a-93b2-8f80e488fdec?ui=en-us&rs=en-us&ad=us.

The new Office software updates changed UI look ‘n feel of Sharing Calendar and managing permissions dialog box. They call it “much simpler user experience when sharing a calendar”. The side burn for this new UI update is that there are two sharing scenarios that are no longer supported.

• Sharing a calendar if you have Full Access permission to your mailbox
• Sharing a calendar if you have Author permission to a mailbox

Sure Microsoft. You had to make our life little harder and call it “much simpler user experience”.

The solution is:

1. Close Outlook

2. Add this Registry Key:

Registry key:
HKCU\Software\Microsoft\Office\16.0\Outlook\Options\Calendar\ShowLegacySharingUX

Type:
UX REG_DWORD

Value: 1

3. Open Outlook and try managing the Calendar permissions now.

Hope this helped you. Enjoy.