How To Fix AQ521 - Table is already being used

SAP Error Message - Details

• Message type: E = Error

• Message class: AQ - Message texts for SAP Query

• Message number: 521

• Message text: Table is already being used

What causes this issue?

The table you attempted to include in the join already exists. This is
not allowed.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message AQ521 - Table is already being used ?

  The SAP error message AQ521, which states "Table is already being used," typically occurs when there is an attempt to perform an operation on a database table that is currently locked or in use by another process. This can happen in various scenarios, such as during data updates, table modifications, or when trying to access a table that is being processed by another transaction.
  Causes:
  
  Concurrent Access: Multiple users or processes are trying to access or modify the same table simultaneously.
  Long-Running Transactions: A transaction that takes a long time to complete may hold a lock on the table, preventing other operations from proceeding.
  Database Locks: The database may have locks in place due to previous operations that have not yet been committed or rolled back.
  Background Jobs: A background job or batch process may be running that is using the table.
  
  Solutions:
  
  Wait and Retry: If the operation is not urgent, wait for a few moments and then retry the operation. The lock may be released once the other transaction completes.
  Check for Locks: Use transaction codes like SM12 (to view and manage locks) to check if there are any active locks on the table. You can identify the user or process holding the lock.
  Kill Long-Running Transactions: If you identify a transaction that is holding a lock for an extended period and is not necessary, you may consider terminating it. This should be done with caution and typically requires appropriate permissions.
  Optimize Transactions: Review the code or processes that are accessing the table to ensure they are optimized and do not hold locks longer than necessary.
  Use Appropriate Isolation Levels: If applicable, consider adjusting the isolation levels of your transactions to reduce locking contention.
  Consult with Basis Team: If the issue persists, it may be beneficial to consult with your SAP Basis team or database administrator to investigate further.
  
  Related Information:
  
  Transaction Codes: Familiarize yourself with transaction codes like SM12 (to view locks), SM21 (to check system logs), and ST22 (to check dumps) for troubleshooting.
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message.
  Documentation: Review SAP documentation regarding database locking mechanisms and best practices for managing concurrent access.
  
  Always ensure that any actions taken to resolve the issue are in line with your organization's policies and procedures, especially when it comes to terminating transactions or modifying database settings.