ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C4H4N2O2/c7-4(8)3-1-5-2-6-3/h1-2H,(H,5,6)(H,7,8)/file?format=sdf&get3d=True  -- InChI=1S/C4H4N2O2/c7-4(8)3-1-5-2-6-3/h1-2H,(H,5,6)(H,7,8) could not be loaded.