ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%26%2361%3B1S/C4H6O2/c1-2-3-4%285%296/h2-3H%2C1H3%2C%28H%2C5%2C6%29/b3-2%2B/file?format=sdf&get3d=True  -- InChI%3DInChI%26%2361%3B1S/C4H6O2/c1-2-3-4%285%296/h2-3H%2C1H3%2C%28H%2C5%2C6%29/b3-2%2B could not be loaded.