I tried to add the following magnet file to bitComet v1.7.1and it keep staying at the waiting for torrent metadata downloading stage forever (at least for hours)
Will it be the case that the file is too old (more than 10 years) that the meta data is removed?
It simply means that it can’t find any trackers. You could try adding them manually, but there is no guarantee that they will have a record of the file in question. That is always a problem with m,agnet downloads (they rely on outside sources for tracker info)
When you download a magnet file, you don’t get any tracker links. They come with a .torrent.
You could, as I said, try manually adding trackers and see if that helps (there are sites containing listings of known active trackers, so google for one and add the tracking data to the client)