How To Fix /IWBEP/CM_MGW_RT182 - Is-Not-Modified is not allowed in case of framework expand

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWBEP/CM_MGW_RT -

• Message number: 182

• Message text: Is-Not-Modified is not allowed in case of framework expand

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message /IWBEP/CM_MGW_RT182 - Is-Not-Modified is not allowed in case of framework expand ?

  The SAP error message /IWBEP/CM_MGW_RT182 Is-Not-Modified is not allowed in case of framework expand typically occurs in the context of OData services when there is an issue with the handling of the HTTP response, particularly when using the $expand query option.
  Cause:
  
  
  HTTP Status Code: The error indicates that the OData service is trying to return a response with a status code of 304 Not Modified while also attempting to use the $expand option. The 304 Not Modified status is used to indicate that the resource has not changed since the last request, and thus the client can use the cached version. However, when expanding entities, the service needs to provide the full data structure, which cannot be satisfied with a 304 response.
  
  
  Caching Mechanism: This error can also arise from the caching mechanism in place, where the client is expecting a full response but the server is indicating that the data has not changed.
  
  
  Service Implementation: There may be an issue in the implementation of the OData service where the handling of the $expand option does not properly account for the Is-Not-Modified scenario.
  
  
  Solution:
  
  
  Check Service Implementation: Review the implementation of the OData service to ensure that it correctly handles the $expand option. Make sure that when $expand is used, the service always returns a full response rather than a 304 Not Modified.
  
  
  Modify Caching Behavior: If caching is causing the issue, consider adjusting the caching behavior. You may need to configure the service to avoid caching for requests that include $expand.
  
  
  Update OData Version: Ensure that you are using a compatible version of the OData service and that it adheres to the specifications regarding $expand and response codes.
  
  
  Debugging: Use debugging tools to trace the request and response cycle. Check the headers and the data being sent and received to identify where the issue may be occurring.
  
  
  SAP Notes: Check for any relevant SAP Notes or updates that may address this specific error. SAP frequently releases patches and updates that can resolve known issues.
  
  
  Related Information:
  
  OData Protocol: Familiarize yourself with the OData protocol specifications, particularly regarding the handling of $expand and HTTP status codes.
  SAP Gateway: If you are using SAP Gateway, review the configuration and settings related to the OData services.
  Client-Side Caching: Understand how the client application is handling caching and whether it can be adjusted to avoid sending requests that expect a 304 Not Modified response when using $expand.
  
  By addressing the above points, you should be able to resolve the error and ensure that your OData service functions correctly with the $expand option.