ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C4H6O/c1-2-4-5-3-1/h1,3H,2,4H2/file?format=sdf&get3d=True  -- InChI=1S/C4H6O/c1-2-4-5-3-1/h1,3H,2,4H2 could not be loaded.