How To Fix /IWFND/CM_GSR021 - Duplicate ID or multiple nodes for an x..1 relation

/IWFND/CM_GSR021 - Overview

• Message type: E = Error

• Message class: /IWFND/CM_GSR -

• Message number: 021

• Message text: Duplicate ID or multiple nodes for an x..1 relation

Self-Explanatory Message

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/IWFND/CM_GSR021 - Details

• The SAP error message /IWFND/CM_GSR021 Duplicate ID or multiple nodes for an x..1 relation typically occurs in the context of SAP Gateway and OData services. This error indicates that there is an issue with the data being returned from the backend system, specifically related to the cardinality of the relationship between entities in the OData model.
  
  Cause:
  
  
  Duplicate IDs: The error suggests that the OData service is trying to return multiple records for a relationship that is expected to have a one-to-one (1..1) or one-to-zero-or-one (0..1) relationship. This can happen if the underlying data model in the database has duplicate entries for a key that should be unique.
  
  
  Incorrect Data Model: The data model defined in the OData service may not accurately reflect the underlying database structure, leading to mismatches in expected relationships.
  
  
  Improperly Defined Associations: If the associations between entities in the OData service are not correctly defined, it can lead to situations