Variant type for node type &1 is not clear

What causes this issue?

There is an error in the Customizing settings. More than one variant
type has been found for the node type you have entered.

System Response

System termination.

How to fix this error?

Notify your administrator.

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.