How To Fix /IWFND/MED_CHECK013 - More than one node for root node '&1'

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWFND/MED_CHECK -

• Message number: 013

• Message text: More than one node for root node '&1'

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message /IWFND/MED_CHECK013 - More than one node for root node '&1' ?

  The SAP error message /IWFND/MED_CHECK013 More than one node for root node '&1' typically occurs in the context of SAP Gateway and OData services. This error indicates that the OData service is trying to retrieve data, but it has encountered multiple root nodes for a single entity, which is not allowed in the OData protocol.
  Cause:
  
  Multiple Root Nodes: The most common cause of this error is that the OData service definition has been incorrectly configured, leading to multiple root nodes being defined for the same entity.
  Data Model Issues: There may be issues in the underlying data model or the way the associations and navigation properties are defined.
  Service Implementation: The implementation of the service might be returning multiple entries for what should be a single root entity.
  
  Solution:
  
  
  Check Service Definition:
  
  Go to the SAP Gateway Service Builder (transaction code SEGW).
  Check the entity types and ensure that there is only one root node defined for the entity in question.
  If you have multiple entities that are being treated as root nodes, consider restructuring your service definition.
  
  
  
  Review Data Model:
  
  Ensure that the data model is correctly defined and that the associations between entities are properly set up.
  Check if the entity set is correctly defined in the service and that it corresponds to a single root entity.
  
  
  
  Debug the Service Implementation:
  
  If you have custom logic in the service implementation (e.g., in the GET_ENTITYSET method), debug the code to ensure that it is returning the expected results.
  Make sure that the logic does not inadvertently return multiple entries for a single root node.
  
  
  
  Test the Service:
  
  After making changes, test the OData service using the SAP Gateway Client (transaction code /IWFND/GW_CLIENT) to ensure that the error is resolved.
  
  
  
  Check for Annotations:
  
  If you are using annotations, ensure that they are correctly defined and do not lead to ambiguity in the service definition.
  
  
  
  Related Information:
  
  OData Protocol: Understanding the OData protocol can help in grasping the importance of having a single root node for each entity.
  SAP Gateway Documentation: Refer to the official SAP documentation for more details on service definitions and best practices.
  SAP Community: Engaging with the SAP Community can provide insights and solutions from other users who may have faced similar issues.
  
  By following these steps, you should be able to identify the cause of the error and implement a solution to resolve it.