Changes only possible in original language

What causes this issue?

You wanted to change the hierarchy in a language other than
the language in which the hierarchy was created. This is not possible.

System Response

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

How to fix this error?

Log on in the language which was used to create the hierarchy.

Error message extract from SAP system. Copyright SAP SE.