Hello, 

An admin will receive an invite due to delegation, for their boss's calendar invites. 

When they select decline, it says "The Operation Failed" So they go to their boss's inbox and try to decline there as well, and get the same descriptive error, "The Operation Failed" 

Any thoughts on this? 

Thanks, 

Will 

Hi,

From your description, I recommend you use the following cmdlet to verify the permission at first.

Get-MailboxFolderPermission -Identity xxx:\calendar |fl

If the permission is not set correctly, you can use the Add-MailboxFolderPermission cmdlet to re-add it and check the result.

Hope this can be helpful to you.

Best regards,

Permissions were checked prior to posting. 

hi,could you please try to remove cached mode for admin account and see if problem is still there?

Is your Outlook version 2013 or 2010?With latest updates?

Please be sure that Boss only has one calendar and its the correct calendar is beeing used/granted permission.

Not in cache mode, using version 2013, and updates are correct. 

Correct calendar with correct permissions 

are you by any chance co-existing your Exchange environment and are users on same Exchange version?

No to co-existing, and yes they are on the same version

Ticket open with Microsoft. 

They can't figure the issue out either....

Hi,have you tried this: https://support.microsoft.com/kb/2697959?wa=wsignin1.0

If above doesnt help,please run the following command in Exchange PowerShell:

Get-MailboxFolderPermission -Identity user@domain.com:\calendar |fl

where user is the owner of the calendar.

Check on the list what kind of permission delegates has (the one getting error Message when try to Accept/decline Meeting.