While testing auto-number functionality in one of our project, we noticed that the auto-number sequence skips, in case of an exception or error while creating the record.
For example: If the previous record sequence number was 1001, the next record sequence number must be 1002. However, if there was an exception while creating the record, the record isn't created in this case. Now if the user creates another record (without exception), the record sequence number would show 1003 (instead of 1002), as that number would have been skipped.
After going through Microsoft's documentation we understood why this happens, as it is clearly mentioned that the number is incremented before the record creation is started and not after the record has been created.
You can access Microsoft's documentation by clicking here.
Hope that helps!
