How To Fix MQ821 - Table &1 (key: &2) has already been locked by user &3

SAP Error Message - Details

• Message type: E = Error

• Message class: MQ - Messages for Euro Changeover Package

• Message number: 821

• Message text: Table &1 (key: &2) has already been locked by user &3

What causes this issue?

Table &V1& cannot be locked for lock argument &V2& since this conflicts
with an existing lock for user &V3&.

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 MQ821 - Table &1 (key: &2) has already been locked by user &3 ?

  The SAP error message MQ821 indicates that a specific table entry (identified by the key) is currently locked by another user. This typically occurs in scenarios where multiple users or processes are trying to access or modify the same data simultaneously, leading to a lock conflict.
  Cause:
  
  Concurrent Access: Another user or process is currently editing or has locked the table entry you are trying to access.
  Long-running Transactions: A transaction that takes a long time to complete may hold locks longer than expected, preventing others from accessing the same data.
  Locking Mechanism: SAP uses a locking mechanism to ensure data integrity. When a user locks a record, other users are prevented from modifying it until the lock is released.
  
  Solution:
  
  Wait and Retry: If the lock is temporary, you can wait for the other user to complete their transaction and then try again.
  Identify the Lock: Use transaction code SM12 to view the list of locks. You can check which user has locked the entry and the duration of the lock.
  Release the Lock: If you have the necessary authorizations, you can manually release the lock from transaction SM12. However, be cautious when doing this, as it may lead to data inconsistencies if the other user is still working on the data.
  Communicate with the User: If you identify the user who has the lock, you can communicate with them to understand if they can release the lock or if they are still working on the data.
  Optimize Transactions: If this is a recurring issue, consider optimizing the transactions to reduce the time locks are held. This may involve reviewing the code or processes that lead to long-running transactions.
  
  Related Information:
  
  Lock Types: Understand the difference between exclusive locks (which prevent any other access) and shared locks (which allow read access but prevent writes).
  Lock Timeout Settings: Review the system settings for lock timeouts, which can be adjusted to minimize the impact of long locks.
  SAP Notes: Check for any relevant SAP Notes that may address specific issues related to locking behavior in your version of SAP.
  Performance Monitoring: Regularly monitor system performance and locking behavior to identify patterns that may lead to frequent lock conflicts.
  
  By following these steps, you should be able to resolve the MQ821 error and minimize its occurrence in the future.