Return
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Title
Error migrating calendar items, "At least one property failed validation., Can't save invalid object Object Violation. Invalid property = [Calc:StartTime] StartTime." -
Description
When migrating calendar items, in rare circumstances, you may experience the following error:
At least one property failed validation., Can't save invalid object Object Violation. Invalid property = [Calc:StartTime] StartTime. Invalid data for that property = Property: [Calc:StartTime] StartTime, PropertyErrorCode: NotFound, PropertyErrorDescription: .. Constraint violated = Property [Calc:StartTime] StartTime is required and must contain a valid DateTime value...
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Resolution
These calendar items will need to be investigated in the source. Check for a valid attributes in the source calendar item by opening the item in Outlook. In this particular scenario, the calendar item was created by the Outlook mobile app, which was also connecting to a personal email account outside of Office 365 and creating invalid calendar entries in Office 365.