How To Fix /IWBEP/CM_V4_MED136 - RefConstr: Non-null NavProp '&1' ('&2'): Invalid nullable for princ/depnt

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWBEP/CM_V4_MED -

• Message number: 136

• Message text: RefConstr: Non-null NavProp '&1' ('&2'): Invalid nullable for princ/depnt

Self-Explanatory Message

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• What is the cause and solution for SAP error message /IWBEP/CM_V4_MED136 - RefConstr: Non-null NavProp '&1' ('&2'): Invalid nullable for princ/depnt ?

  The SAP error message /IWBEP/CM_V4_MED136 RefConstr: Non-null NavProp '&1' ('&2'): Invalid nullable for princ/depnt typically occurs in the context of OData services when there is an issue with the navigation properties defined in the data model. This error indicates that there is a problem with the cardinality or nullability of the navigation properties between entities in your OData service.
  Cause:
  
  
  Navigation Property Configuration: The error suggests that there is a navigation property that is expected to be non-null (i.e., it must always have a value) but is defined in a way that allows it to be nullable. This can happen if the relationship between the principal (parent) and dependent (child) entities is not correctly defined.
  
  
  Cardinality Mismatch: The cardinality defined in the data model (e.g., one-to-many, many-to-one) may not match the actual data or the way the entities are related. For example, if a principal entity is expected to have a mandatory relationship with a dependent entity, but the dependent entity is defined as optional, this can lead to the error.
  
  
  Model Definition Issues: There may be inconsistencies in the way the entities and their relationships are defined in the ABAP CDS views or the OData service metadata.
  
  
  Solution:
  
  
  Check Entity Relationships: Review the relationships between the entities in your data model. Ensure that the navigation properties are correctly defined with the appropriate cardinality and nullability. If a navigation property is supposed to be non-null, ensure that the corresponding relationship is defined as mandatory.
  
  
  Update CDS Views: If you are using Core Data Services (CDS) views, check the definitions of the views to ensure that the relationships and annotations are correctly specified. You may need to adjust the @EndUserText.label and @ObjectModel.association annotations to reflect the correct cardinality.
  
  
  Adjust OData Service Metadata: If you have made changes to the underlying data model, regenerate the OData service metadata to ensure that it reflects the current state of the model. This can often be done through transaction /IWFND/MAINT_SERVICE in the SAP GUI.
  
  
  Test with Sample Data: After making changes, test the OData service with sample data to ensure that the navigation properties behave as expected and that the error no longer occurs.
  
  
  Consult Documentation: If you are unsure about the correct configuration, refer to the SAP documentation on OData services and entity relationships for guidance on how to properly define navigation properties.
  
  
  Related Information:
  
  OData Services: Understanding how OData services work in SAP, including the concepts of entities, navigation properties, and relationships.
  ABAP CDS Views: Familiarity with Core Data Services (CDS) and how to define entities and their relationships in ABAP.
  SAP Notes and Community: Check SAP Notes for any known issues or patches related to this error, and consider reaching out to the SAP Community for additional support and insights from other developers who may have encountered similar issues.
  
  By following these steps, you should be able to resolve the error and ensure that your OData service functions correctly.