How To Fix MD_ODATA002 - No ETag was received

SAP Error Message - Details

• Message type: E = Error

• Message class: MD_ODATA - Messages for master data oData services

• Message number: 002

• Message text: No ETag was received

Self-Explanatory Message

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.

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Smart SAP Assistant

• What is the cause and solution for SAP error message MD_ODATA002 - No ETag was received ?

  The SAP error message MD_ODATA002: No ETag was received typically occurs in the context of OData services when the system is unable to retrieve an ETag (Entity Tag) for a resource. ETags are used in HTTP to determine whether a resource has changed, allowing for efficient caching and conditional requests.
  Cause:
  
  Service Configuration Issues: The OData service may not be properly configured to return ETags. This can happen if the service is not set up to include ETag headers in its responses.
  Backend Issues: There may be issues in the backend system that prevent it from generating or sending ETags.
  Network Issues: Intermittent network issues or misconfigurations can lead to incomplete responses from the server.
  Caching Problems: If there are caching mechanisms in place (either on the client or server side), they may interfere with the retrieval of ETags.
  
  Solution:
  
  
  Check OData Service Configuration:
  
  Ensure that the OData service is configured to return ETags. This may involve checking the service implementation in the SAP Gateway or the backend system.
  Verify that the service is correctly exposing the necessary metadata.
  
  
  
  Review Backend Logic:
  
  If you have access to the backend logic, check if the ETag is being generated and sent correctly. This may involve debugging the service implementation.
  
  
  
  Test the Service:
  
  Use tools like Postman or SAP Gateway Client (Transaction /IWFND/GW_CLIENT) to manually test the OData service and check if ETags are being returned in the response headers.
  
  
  
  Check Network Configuration:
  
  Ensure that there are no network issues or misconfigurations that could be affecting the communication between the client and the server.
  
  
  
  Clear Cache:
  
  If caching is involved, try clearing the cache on both the client and server sides to see if that resolves the issue.
  
  
  
  Consult Documentation:
  
  Refer to SAP documentation or community forums for any specific notes or updates related to the OData service you are using.
  
  
  
  Related Information:
  
  ETag Usage: ETags are primarily used for cache validation and to optimize network usage. They help in determining if the resource has changed since the last request.
  OData Protocol: Understanding the OData protocol and how it handles requests and responses can provide insights into how ETags are managed.
  SAP Notes: Check for any relevant SAP Notes that might address known issues or provide patches related to OData services and ETags.
  
  If the issue persists after trying the above solutions, consider reaching out to SAP support for further assistance, providing them with detailed information about the error and the context in which it occurs.