select your path, and make sure your on the surface menu and not on polygon one, click on the surface tab on top and chose planar, click on the option box next to it and a window should pop up, use the followign setting: Degree: Linear Curve Range: complete Output Geometry: Polygon Attach multiple output meshes and Match render tessellation: leave those 2 options unchecked Type: Quads Tessellation Method: standard fit and leave every setting below to their default. you should get a polygon mesh that can be extruded