Dynamic Data Flow - "... is DT_NTEXT, which is not supported with ANSI files" when trying to process input Unicode flat file

Dynamic Data Flow - "... is DT_NTEXT, which is not supported with ANSI files" when trying to process input Unicode flat file

Trying to process input Unicode flat file fails with weird error:

The data type for "Flat File Source.Outputs[Flat File Source Error Output].Columns[Flat File Source Error Output Column]" is DT_NTEXT, which is not supported with ANSI files. Use DT_TEXT instead and convert the data to DT_NTEXT using the data conversion component.

We believe there is a validation bug in the Flat File Source component. The solution is to set ValidateExternalMetadata=True on the Flat File Source component and set DelayValidation=True on the Data Flow Task Plus.