I kept getting this pesky error, with no apparent solution found online. It happened when copy-pasting coordinates from files in different platforms. I edited the input file many many times in Linux but only when I got to look at it in a Windows Notepad was that I saw the following lines: 6 0.000000000 0.000000000     -0.030561000 Where the “” symbols had to be removed by deleting every apparently empty space between coordinates.