How To Fix MODEL021 - Header table '&1' locked

SAP Error Message - Details

• Message type: E = Error

• Message class: MODEL - Modeling

• Message number: 021

• Message text: Header table '&1' locked

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message MODEL021 - Header table '&1' locked ?

  The SAP error message MODEL021 indicates that a header table (denoted by &1) is currently locked. This typically occurs when a transaction is trying to access or modify a table that is already being used by another process or user. Here’s a breakdown of the cause, potential solutions, and related information:
  Cause
  
  Concurrent Access: Another user or process is currently accessing the header table, causing a lock.
  Long-running Transactions: A transaction that takes a long time to complete may hold a lock on the table longer than expected.
  Uncommitted Changes: If a previous transaction did not commit or rollback properly, it may leave the table in a locked state.
  System Issues: Sometimes, system issues or bugs can lead to unexpected locks.
  
  Solutions
  
  Wait and Retry: If the lock is temporary, waiting for a few moments and then retrying the operation may resolve the issue.
  Identify the Lock:
  
  Use transaction SM12 to view and manage locks. You can see which user or process is holding the lock on the header table.
  If you have the necessary authorizations, you can delete the lock entry if it is safe to do so (e.g., if the user is no longer active).
  
  
  Check for Long-running Transactions: Use transaction SM66 or SM50 to monitor active processes and identify any long-running transactions that may be causing the lock.
  Review Code: If you are developing or maintaining custom code, ensure that database operations are properly committed or rolled back to avoid leaving locks in place.
  System Restart: In extreme cases, if the lock cannot be resolved, a system restart may be necessary, but this should be done with caution and typically as a last resort.
  
  Related Information
  
  Lock Management: Understanding how SAP handles locks can help in troubleshooting. SAP uses a locking mechanism to prevent data inconsistencies during concurrent access.
  Transaction Codes:
  
  SM12: To view and manage locks.
  SM66: To monitor active processes across the system.
  SM50: To view processes on the local instance.
  
  
  Documentation: Refer to SAP Help documentation for more details on locking mechanisms and best practices for managing locks.
  
  Best Practices
  
  Regularly monitor and manage locks in the system to prevent issues.
  Ensure that all transactions are designed to commit or rollback changes appropriately.
  Educate users on the importance of completing transactions to avoid leaving locks in place.
  
  If the issue persists after trying the above solutions, it may be necessary to consult with your SAP Basis team or SAP support for further assistance.