SAP Note 19050 - Gaps in document number sequence for billing docmts

Symptom:

When you create billing documents in VF04 or in the background, there are sometimes gaps in the number assignment.

Reason and Prerequisites

1. Update terminations have occurred. This can be seen in the syslog.

2. The RV_BELEG number object is buffered (Transaction SNUM).

3. An error occurs between number assignment and COMMIT WORK.

Solution
For 3)
Customizing activities may occasionally change a program to be carried out after number assignment. As this happens while the program is running, a termination occurs (for example during output determination).