Account assignment object &1 is locked

What causes this issue?

Account assignment object (product cost collector) &V1& is currently
locked by another user.

System Response

The posting cannot be made.

How to fix this error?

Attempt the posting again later.

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.