Invalid non-recurring appointment start date: This error indicates that the calendar item is non-recurring and has an invalid start date. This typically happens for old appointments which have become corrupted, or for appointments which were incorrectly created by a third-party application (such as a sync or CRM application).
Resolution:
We recommend the following:
- Log the subject of failed items..
- Retry failed items (subjects will be logged)
- Review error logs to identify the offending calendar items.
- Fix the start/end date (i.e., open and save each calendar item).