171: Invalid @header value

The header metadata name is declared to turn the automatic integration of a @header.nml file off or to link a header file manually. However, the assigned value is neither off nor a link in your case.

Solution

Assign the value off to turn the automatic integration of a @header.nml file off:

@ header: off

Use an arrow before the filepath, if you want to point to a header file manually:

@ header: ->/my/banner.nml