My computer says your download is corrupt and will not download it. Why?

My computer says your download is corrupt and will not download it. Why?

Please don’t post as wiki.

A file may come corrupted when downloaded for various reasons:

  • a broken file served from a mirror (hosted by an external party)
  • wrong metadata reported by a mirror for a download (which makes some browsers/downloaders to modify downloads on saving)
  • network errors

Some of the problems could be fixed by re-downloading a file; but sometimes one needs to select a different downloader program, mirror, or even download method (e.g., using torrent). If you have identified a broken mirror serving wrong file, you could also tell us using our mailing list, which could help us fix that kind of problems.