Message type: E = Error
Message class:  SLAD - SLAD: Messages for "Layer Aware Debugging" 
Message number: 120
Message text: Object &1 is locked; choose another name
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The SAP error message SLAD120 indicates that an object (such as a data element, domain, or other repository object) is currently locked and cannot be modified or created with the same name. This typically occurs when another user or process is currently working on that object, or if a previous session did not release the lock properly.
Cause: Concurrent Access: Another user is currently editing or has locked the object. Unreleased Locks: A previous session may have left the object locked due to an error or improper termination. Transport Requests: The object might be part of a transport request that is currently being processed.
Solution: Check Lock Status: Use transaction code SM12 to check for locks on the object. You can filter by the object name or user to see if it is locked by another user. If you find that the object is locked by a user who is no longer active, you can delete the lock
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