hi, Please first run the cmd to make sure that the owner permission has been added: get-mailboxfolderpermission -identity your user name:\calendar If the permission has been added, and the issue still occur. Please try to recreate outlook profile, see if it can help you to fix your issue. hope can help you thanks,CastinLu TechNet Community Support

Getting the dialogue box on the task bar as soon as tried to access the shared calendar. Microsoft Office Outlook Yod do not have sufficient permission to perform this operation on this object. See the folder contact of your system administrator. Further getting the event ID 25 with the above message in the user computer. Even provided owner level access in delegation just to check, but no luck. any info on the same would be appreciated. Thanks, vinod

hi, Please first run the cmd to make sure that the owner permission has been added: get-mailboxfolderpermission -identity your user name:\calendar If the permission has been added, and the issue still occur. Please try to recreate outlook profile, see if it can help you to fix your issue. hope can help you thanks,CastinLu TechNet Community Support