How to solve the Calendar not Opening an issue in a Hybrid Exchange Environment? That’s why when the user makes a query, the scheduling service checks the organization relationship which is attached to the default account and acts on calendar information like Free/Busy, time, subject, location. The cause behind the unavailability of calendar details in Office 365 is that the default permissions of a calendar are set to ‘None.’ When the user makes a query to the scheduling assistant, the scheduling service functions based on the organization relationship rather than the user’s permissions. Remove the calendar and try to add it again or ask the owner to share it again.“įurthermore, the users cannot access the information in the Scheduling Assistant for the user’s mailbox, and the user gets the error ‘Could not be updated.’ Reasons Behind the Calendar Inaccessibility issue in a Hybrid Exchange Environment “ A connection couldn’t be made with the shared calendar. Here are some errors which users face in such cases: Sometimes in a hybrid environment, when Exchange Online (Office 365) users try to open their on-premises calendar, they may face issues.