Solution : https://service.sap.com/sap/support/notes/175047 (SAP Service marketplace login required)
Summary : 
      RFBNUM00 and RFBNUC00N reports in SAP highlight an issue with document number gaps in the number range object RF_BELEG, contrary to legal requirements for continuous FI document number assignment, as observed in Germany. A seemingly archived FI document not displaying due to a nonexistent archiving indicates a discrepancy between document number reservation and actual database updates. Gaps result either from update terminations or from errors in the transaction's online segment, potentially leaving a gap if errors remain uncorrected. Mitigation includes processing failed updates according to specified SAP Notes and ensuring proper documentation of update terminations within 50 days.
Key words : 
fi document number = sd document number, rfbnum00--------------------------------------------rfbnum00 displays wrong gaps, call transaction 'fb02' mode 'e', missing document number gaps caused, rfbnum00 displays wrong gaps, open fi callup point 00001030, occurrence ofdocument number gaps, system parameter 'rdisp/vbdelete', terms data base inconsistency, number range object rf_beleg
Related Notes : 
       
| 1522367 | Document number gap reason and analysing method | 
| 1513587 | How to analyze an update termination | 
| 1420715 | FBV1: Gaps in doc number assgmt in parking due to error msg | 
| 1259205 | FI: Document number gaps in FI documents due to error msgs | 
| 743744 | MIRO/MR1M: FI follow-on documents or MM documents missing | 
| 585513 | Inexplicable document number gaps in FI (III) | 
| 486103 | (FI+MM) Change parked document header: Performance | 
| 450520 | FBZ4: Paymt doc. missing for outgoing paymt w/ check print | 
| 428391 | Inexplicable document number gaps in FI (II) | 
| 390658 | RFBNUM00: error message FR264 | 
| 378178 | (FI) Changing parked document as regards posting year | 
| 365093 | Inexplicable document number gaps in FI | 
| 363790 | MR01: Gaps in document number assignment | 
| 324195 | FB60:RW012 'Error when...'after one-time processing | 
| 318782 | Gap in document number assignment for FS215/FS216 | 
| 304889 | FBV4: Gap in document number after "Back" | 
| 193020 | Invoice verification: Gaps in number assignment | 
| 179224 | Doc.no.assignment for unbuffered number ranges | 
| 148757 | RFBNUM00 displays wrong gaps in document numbers | 
| 144779 | RFBIBL00 'D': F5312 but no document display possible | 
| 144487 | Missing lines in logical cluster tables | 
| 142922 | RFVBER00: Scope of functions compared to SM13 | 
| 136482 | Missing documents when updating in batch input | 
| 127565 | Document number range full but no warning message | 
| 119350 | Problems during the local update | 
| 115222 | RFBNUM00 does not select clearing documents | 
| 102353 | Update control | 
| 95614 | Correction program:missing FI documents f. invoices | 
| 95317 | Analysis: Billing docs available/accounting docs missing | 
| 86447 | RWIN: Incomplete documents | 
| 84926 | RFBIBL00: transaction is lost | 
| 77419 | VF076 for billing docs. w. net value unequal zero | 
| 75797 | VF04: Gaps in doc. nos. after update termination | 
| 74963 | Double update in invoice verification | 
| 74096 | SAPFF001 & LFACIF05: F5302 document is locked | 
| 70085 | Subsequently processing canceled update records via SM13 | 
| 64725 | Double material documents | 
| 63702 | RFVBER00: Functionality / list range | 
| 62077 | Info: Internal number assignment is not continuous | 
| 44978 | Problems with RFBNUM00 | 
| 37844 | Performance: document number assignment RF_BELEG | 
| 24279 | Missing billing document numbers in VBRK | 
| 23835 | Buffering RV_BELEG / Number assignment in SD | 
| 19050 | Gaps in document number sequence for billing docmts |