IrfanView: Can't Read File Header, Unknown file format

If the image files you're unable to open were obtained via download to a folder name that includes certain special characters (for example, the symbols seen in "【Pictures】") this creates a file path that, although acceptable to the operating system, is not recognized properly by IrfanView (or other apps), yielding the somewhat misleading "Can't Read File Header, Unknown file format" message (should really say "File Not Found"). Simple solution is to rename the download folder, or move the image files to another directory with a name that's recognized properly by IrfanView. Hope this helps some who are encountering this confusing error!