Sam G., try saving your rasters to the desktop, that is what i have been doing, and work from there. You need to get rid of temporary files.

Sounds good. 1. New project, load band 1 of 3-band tiff, classify into 2 values; 2. Create new polyline shapefile and set coordinate system; 3. start editing and 4. VOILA! Thanks, it seems that I really did need to create polyline shapefile, not a polygon feature class, which is what I initially tried (and, in fact, what the error told me to do all along...how embarrassing).

I'm using the centerline method. I am specifically trying to avoid "outline vectorization" (that happened when I outsourced my difficulties to a friend who used Adobe Illustrator). I am stuck at "Generate Features" or Step 7 from here (gisgeography.com/how-to-vectorize-image-arcscan). In other words, I'm not able to "post-process" anything because I can't seem to figure out how to make it run in the first instance. When I hit "Generate Features," it throws me the error that I quoted in the original post. I created a blank feature class, not shapefile, I will try blank shapefile now...

I'm trying to create a polygon layer from a raster, that's what ArcScan vectorization does. So no, unless I'm misunderstanding something, why would I have an "editable polyline layer" if that is what I am trying to create? This thread regards the same question (geonet.esri.com/thread/22940), though doesn't seem to have ever been answered. Thanks.

Gotcha, thanks. Tried that without luck. I've also tried working on 1 band at a time and then also saving to a Temp folder. When I try to save to C:Users/myname/AppData/Local/Temp, I get the error "ERROR 6: GDALDriver::Create() ... no create method implemented for this format." Perhaps I don't have permission to save there or ?

How do I display the python script running the gdal_fillnodata plugin so that I can copy and paste it directly into the GDAL commandline? Thank you.

I tried to but it would only let me provide 2 links, i.e. the two attachment pics, because I don't have 10 reputation points yet. But will in the future.