How To Fix E0651 - Extension not possible: Segment type & occurs twice

SAP Error Message - Details

• Message type: E = Error

• Message class: E0 - SAP EDI messages

• Message number: 651

• Message text: Extension not possible: Segment type & occurs twice

What causes this issue?

The segment type &v1& occurs in the basic type &v2& and in the
extension &v3&. However, it is not a reference segment type.
Note:
The reason for the error may also be that the basic type &v2& and the
extension &V3& are to be combined automatically.

System Response

The combination is impossible.

How to fix this error?

Choose a basic type and an extension for which the segment types of one
component do not occur in the other.
The reference segment types of the extension must, however, occur in
the basic type.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message E0651 - Extension not possible: Segment type & occurs twice ?

  The SAP error message E0651, which states "Extension not possible: Segment type & occurs twice," typically occurs in the context of data modeling or when working with IDocs (Intermediate Documents) in SAP. This error indicates that there is an issue with the structure of the data segments being defined, specifically that a segment type is being defined more than once in a way that is not allowed.
  Cause:
  
  Duplicate Segment Definition: The error usually arises when a segment type is defined multiple times in the same context or structure. For example, if you are trying to extend a segment type in an IDoc or a data structure, and that segment type is already defined, SAP will throw this error.
  Incorrect Data Model: The data model may not be correctly designed, leading to conflicts in segment definitions.
  Configuration Issues: There may be issues in the configuration of the IDoc or data structure that lead to the same segment being referenced multiple times.
  
  Solution:
  
  Check Segment Definitions: Review the segment definitions in your IDoc or data structure. Ensure that each segment type is defined only once and that you are not trying to extend a segment that has already been defined.
  Modify Data Model: If you need to include the same segment type multiple times, consider redesigning your data model to accommodate this requirement without duplicating segment definitions.
  Use Unique Names: If you are creating extensions, ensure that the names of the segments are unique and do not conflict with existing segment types.
  Consult Documentation: Refer to SAP documentation or guidelines for creating IDocs or data structures to ensure compliance with best practices.
  Testing: After making changes, test the configuration to ensure that the error is resolved and that the data structure behaves as expected.
  
  Related Information:
  
  IDoc Structure: Understanding the structure of IDocs and how segments are defined is crucial. Each segment can have a specific structure and should be unique within the context of the IDoc.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message. Sometimes, there may be specific fixes or recommendations provided by SAP.
  Transaction Codes: Familiarize yourself with relevant transaction codes such as WE30 (IDoc Type Development) and WE31 (Segment Definition) to manage and troubleshoot IDoc structures effectively.
  
  If the problem persists after following these steps, it may be beneficial to consult with an SAP expert or reach out to SAP support for further assistance.