How To Fix /IWBEP/CM_V4_APPS018 - A precondition (ETag) of the request does not match

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWBEP/CM_V4_APPS -

• Message number: 018

• Message text: A precondition (ETag) of the request does not match

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message /IWBEP/CM_V4_APPS018 - A precondition (ETag) of the request does not match ?

  The SAP error message /IWBEP/CM_V4_APPS018 indicates that there is a mismatch in the ETag (Entity Tag) of the request. This typically occurs in the context of OData services when a client attempts to update or delete a resource, but the ETag provided in the request does not match the current ETag of the resource on the server. This is a mechanism used for optimistic concurrency control to prevent lost updates.
  Cause:
  
  
  ETag Mismatch: The ETag value sent in the request header does not match the current ETag value of the resource on the server. This can happen if:
  
  The resource was modified by another user or process after the client retrieved it.
  The client is using an outdated ETag value.
  
  
  
  Caching Issues: If the client is caching the ETag and not refreshing it before making the request, it may lead to this error.
  
  
  Concurrency Control: The application logic may not be handling concurrent updates properly, leading to stale ETag values being used.
  
  
  Solution:
  
  
  Refresh ETag: Ensure that the client retrieves the latest version of the resource before making an update or delete request. This can be done by performing a GET request to fetch the current state of the resource, which will include the latest ETag.
  
  
  Check for Updates: Implement logic in the application to check for updates to the resource before attempting to modify it. This can help avoid conflicts.
  
  
  Handle Errors Gracefully: Implement error handling in the application to manage this error gracefully. For example, if an ETag mismatch occurs, the application can prompt the user to refresh the data and try again.
  
  
  Review Application Logic: Ensure that the application logic correctly manages the lifecycle of resources and their ETags, especially in scenarios involving multiple users or processes.
  
  
  Related Information:
  
  ETag: An ETag is a unique identifier assigned to a specific version of a resource. It is used in HTTP to determine if the resource has changed since the last request.
  Optimistic Concurrency Control: This is a strategy used to handle concurrent updates to a resource. It allows multiple transactions to occur without locking the resource, but it requires checks (like ETags) to ensure that updates do not overwrite each other.
  OData Protocol: OData (Open Data Protocol) is a standard protocol for building and consuming RESTful APIs. Understanding how OData handles ETags and concurrency can help in troubleshooting related issues.
  
  By following these steps and understanding the underlying concepts, you should be able to resolve the /IWBEP/CM_V4_APPS018 error effectively.