Office 365 Calendar Troubleshooting

Here is a link for good information on this: Admin Approval Flow.

Known Error States

Error	Description
Failed	Access to the calendar is denied due to insufficient user permissions. Please check and ensure you have the necessary permissions for the specified calendar.
Failed	Important fields in the calendar (body) that are necessary for parsing are missing. User access to these fields is likely restricted, either deliberately or accidentally.
Failed	Unable to locate the specified calendar. Verify that the calendar actually exists and the name provided is correct.
Failed	New access tokens for the tenant are unavailable because the app was removed. App re-integration is required.
Failed	New access tokens for the tenant can't be obtained because the app permissions were revoked. Re-adding permissions or re-integrating the app is required.
Failed	Unexpected delays (timeouts), server errors (5xx errors), or connectivity issues have occurred. Calendar service provider may be experiencing an outage.
Failed	Something broke that we have never encountered. Please wait and try again.