Type of DataSource &1 is not supported; see long text

What causes this issue?

The DataSource &V1& belongs to type &V2&.
This DataSource type is not supported by model transformation.
The following types of DataSources are supported:
Flow data
Master data text

System Response

The model transformation process is terminated.

How to fix this error?

Select a valid DataSource.

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.