Error: Could not draw the PolyArc Shape with apertures listed in < xxx.gmf > file. Please add smaller aperture to draw the PolyArc Shape
The error is due to either using "274D" Data type in the Gerber Machine Formet file (.gmf).
Or the .gmf file is using "274X" but with the "Polygon fill method" set to "Draw".
The solution is to set the .gmf file data type to "274X" and the "Polygon fill method" set to Raster.
<Note> The setting of .gmf file can be invoked from Menu: Setup > Gerber Machine Format....