Message type: E = Error
Message class:  /IWBEP/SBUIOD -  
Message number: 064
Message text: Enter the Cardinality for Principal Entity.
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The SAP error message /IWBEP/SBUIOD064 Enter the Cardinality for Principal Entity typically occurs in the context of SAP Gateway or SAP Fiori applications when defining or configuring OData services. This error indicates that the cardinality for a principal entity in a data model is not specified, which is necessary for establishing relationships between entities.
Cause: Missing Cardinality Definition: The cardinality (e.g., one-to-one, one-to-many, many-to-many) for a principal entity in the OData service is not defined. This is essential for the system to understand how entities relate to each other. Model
Configuration Issues: There may be issues in the configuration of the data model, such as missing or incorrect relationships between entities. Incomplete Metadata: The metadata for the OData service may be incomplete or incorrectly defined, leading to this error.
Solution: Define Cardinality: Go to the relevant data model in the SAP Gateway Service Builder (transaction code SEGW). Locate the entity that is causing the error. Ensure that the cardinality
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