How To Fix FKKINV006 - Doc. with external document number &1 logical system &2 already exist

FKKINV006 - Overview

• Message type: E = Error

• Message class: FKKINV - Invoicing in Contract Accounts Receivable and Payable

• Message number: 006

• Message text: Doc. with external document number &1 logical system &2 already exist

What causes this issue?

A billing document already exists with <DS:DE.REFDOCNO_KK>external
document number</> &V1& from <DS:DE.LOGSYS>logical system</> &V2&.

System Response

The billing document is inconsistent and cannot be saved.

How to fix this error?

For each logical system select unique values for the external document
number.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message FKKINV006 - Doc. with external document number &1 logical system &2 already exist ?

  The SAP error message FKKINV006 indicates that there is an attempt to create a document (usually an invoice) with an external document number that already exists in the system for a specific logical system. This typically occurs in the context of SAP Convergent Charging or SAP Contract Accounts Receivable and Payable (FI-CA).
  
  Cause:
  The error is caused by the following reasons:
  
  Duplicate External Document Number: The external document number you are trying to use for the invoice already exists in the system for the specified logical system. This can happen if the same external document number is being reused or if there was a previous transaction that was not properly cleared.
  Logical System Configuration: The logical system specified in the error message may be configured to prevent duplicate entries for external document numbers.
  
  
  Solution:
  To resolve the error, you can take the following steps:
  
  
  Check Existing Documents:
  
  Use transaction codes like FBL1N, FBL3N, or FBL5N to search for