ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1S/C2H2O4/c3-1(4)2(5)6/h(H,3,4)(H,5,6)/file?format=sdf&get3d=True  -- InChI=1S/C2H2O4/c3-1(4)2(5)6/h(H,3,4)(H,5,6) could not be loaded.