Error importing shape files classification

I just downloaded the Snap S2 Toolbox. I´m working on my thesis and just discovered this tool.
I tried a classification and the first error appeared already while loading the shapefiles for training. I just worked for 2 of 5 files. Whats wrong with the other files? All files consist of 10 - 15 training areas.
Thanks for your help!

Another question: Can I safe all layer as single tiff files?

could have many reasons:

  • bad naming (are spaces or special characters in the filename?)
  • bad geometries (are there any sliver polygons or topology errors?)
  • bad reference (are all parts of the shapefile included?)

You can export S2 as GeoTiff by Menu > File > Export
but you are asked to resample it to a common resolution first. Confirm with ‘yes’ and then export the resampled product.