ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C4H6O4/c5-1-3-2-7-4(6)8-3/h3,5H,1-2H2/file?format=sdf&get3d=True  -- InChI=1S/C4H6O4/c5-1-3-2-7-4(6)8-3/h3,5H,1-2H2 could not be loaded.