Hierarchy is at present blocked against changes

What causes this issue?

User &V1& is currently working on the cost center group or the entire
standard hierarchy. At the moment you cannot assign the cost center to
another group or create a new cost center, since these changes also
affect the standard hierarchy.

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

System Response

How to fix this error?

Check whether you are running the transaction in another session or
wait until the user has finished processing. Contact the other user if
necessary.

Error message extract from SAP system. Copyright SAP SE.