Message type: E = Error
Message class:  /IWPGW/PGW_SERVICE -  
Message number: 103
Message text: Attribute &1 is not a key for entity &2
Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.
To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.
Unfortunately, there isn't any extra information in this error notice.
First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).
Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.
You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.
The SAP error message /IWPGW/PGW_SERVICE103 Attribute &1 is not a key for entity &2 typically occurs in the context of SAP Gateway services, particularly when working with OData services. This error indicates that there is an issue with the way the attributes are defined in the OData service, specifically regarding the key attributes of an entity.
Cause: Incorrect Key Definition: The attribute specified in the error message (&1) is being used as a key for the entity (&2), but it is not defined as a key in the entity's metadata. Model Mismatch: There may be a mismatch between the data model in the backend and the OData service definition. If the OData service is expecting a certain key attribute that is not defined in the underlying data model, this error will occur. Service Metadata Issues: The service metadata might not be correctly generated or updated, leading to inconsistencies in the key definitions.
Solution: Check Entity Definition:
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
/IWPGW/PGW_SERVICE102 Could not determine service name and service version
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
/IWPGW/PGW_SERVICE101 Could not get the process facade proxy instance
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
/IWPGW/PGW_SERVICE104 SAP Gateway context parameter &1 is empty
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
/IWPGW/PGW_SERVICE105 SAP Gateway context attribute &1 is not bound
Self-Explanatory Message Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of...
Click on this link to search all SAP messages.