Realignment run running or terminated, hierarchy processing not possible

What causes this issue?

You cannot process the hierarchy, since the change run containing this
hierarchy is either running currently, or has been terminated.

How to fix this error?

If the change run has been terminated, remove the error that caused the
termination, and run the change run from the beginning again. Once the
change run is complete, you are able to work on the hierarchy again.

Error message extract from SAP system. Copyright SAP SE.