& is locked

What causes this issue?

Object is locked.

System Response

Current action will be terminated.

How to fix this error?

End the transaction.
Recall the transaction at a later date. If the object is still locked,
check whether any still unreleased transport requests that contain the
current object still exist.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.