ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%26%2361%3B1S/C4H8N2O/c1-3-5-6%282%294-7/h3-4H%2C1-2H3/file?format=sdf&get3d=True  -- InChI%3DInChI%26%2361%3B1S/C4H8N2O/c1-3-5-6%282%294-7/h3-4H%2C1-2H3 could not be loaded.