Invoice number range skipping

There are a number of reasons why gaps in invoice numbers may occur:
1. Number range object is buffered. Please refer to note 62077 for details.
2. Update terminate/short dump occurs while billing document update.- the number is set in to the invoice at the beginning of the program If an interruption of the process happens after the assignation of this number, the number has run in the range and cannot be recovered. Update terminations in transaction VF01 and VF04. The billing document number is reserved prior to the update. After a possible update termination, it cannot be used again. Update terminations are displayed in transaction SM13. At present, there is no possible solution.
3. Incorrect user exit, eg. in Program RV60AFZZ, USEREXIT_NUMBER_RANGE.
Please check the following notes in order to solve this incidence: 175047 Causes for FI document number gaps (RF_BELEG) 19050 Gaps in document number sequence for billing document.
Unfortunately nothing much can be done on the missing/gaps on invoices as this problem happen randomly & not able to reproduce.
As you might need to answer to the auditor on the gap of the invoices, report RFBNUM00 from note 175047 will help you to display document number gaps to the auditor if in your country the FI document numbers must be assigned continuously. You use this report to document the number gaps and the auditor will accept it.
It is known that in different countries you have to explain document gaps to Legal Authorities. For this reason there is report RFVBER00 to document gaps occurred due to an update termination.
As already stated above report RFVBER00 does only list update terminations that are not older than 50 days (or according to what time is maintained in your system). So it could be that this log has already been cleaned up. It is necessary that these update terminations are documented before the 50 days expire.
Or a second possibility is that the gaps occurred NOT due to an update termination. Gaps without update terminations be (easily) explained. They can be (only) detected via report RFBNUM00. Report RFBNUM00 display these document number gaps for the number range object RF_BELEG.