Only company code & can be assigned

What causes this issue?

If the <GL:assignment_control>assignment control</> indicator is set to
1, you cannot chose the controlling area key freely. It must be
identical to the assigned company code key. You can only change the
assignment to controlling area &V1& because the controlling area name
&V1& has already been defined.

How to fix this error?

Change the assignment so that only company code &V1& is still assigned.

Error message extract from SAP system. Copyright SAP SE.