How To Fix WB2_SE_TRO021 - Exactly-once request cannot be locked: &1 (error code &2)

SAP Error Message - Details

• Message type: E = Error

• Message class: WB2_SE_TRO - Message Class for Trading Order Services

• Message number: 021

• Message text: Exactly-once request cannot be locked: &1 (error code &2)

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message WB2_SE_TRO021 - Exactly-once request cannot be locked: &1 (error code &2) ?

  The SAP error message WB2_SE_TRO021 indicates that a request cannot be locked because it is already being processed or is in a state that prevents it from being locked for an exactly-once processing scenario. This error typically occurs in the context of SAP's Event Management or Process Integration (PI) scenarios where exactly-once processing is crucial to ensure data integrity and consistency.
  Cause:
  
  Concurrent Processing: The request identified by the key (e.g., &1) is already being processed by another transaction or session. This can happen if multiple processes are trying to handle the same request simultaneously.
  Locking Mechanism: SAP uses a locking mechanism to prevent data inconsistencies. If a request is already locked by another process, any subsequent attempts to lock it will result in this error.
  Long-Running Transactions: If a transaction takes too long to complete, it may hold the lock longer than expected, leading to this error for other processes trying to access the same request.
  
  Solution:
  
  Check for Active Processes: Use transaction codes like SM12 (to check for locks) and SM21 (to check system logs) to identify if another process is currently holding the lock on the request.
  Wait and Retry: If the request is being processed by another transaction, you may need to wait for that transaction to complete before retrying your operation.
  Review Application Logic: Ensure that your application logic is designed to handle locking appropriately. This may involve implementing retry mechanisms or ensuring that requests are not processed concurrently when they shouldn't be.
  Increase Timeout Settings: If long-running transactions are common, consider reviewing and possibly increasing the timeout settings for locks in your SAP system.
  Consult SAP Notes: Check for any relevant SAP Notes that may address this specific error or provide additional guidance on handling locking issues.
  
  Related Information:
  
  Transaction Codes: Familiarize yourself with transaction codes like SM12 (to view and manage locks), SM21 (to view system logs), and ST22 (to check for dumps).
  SAP Documentation: Review SAP documentation related to the specific module you are working with (e.g., Event Management, Process Integration) for best practices on handling exactly-once processing and locking mechanisms.
  Performance Monitoring: Regularly monitor system performance and transaction durations to identify potential bottlenecks that could lead to locking issues.
  
  If the problem persists after trying the above solutions, it may be beneficial to engage with your SAP Basis team or SAP support for further assistance.