M3U8 is a UTF-8 playlist format widely associated with HTTP Live Streaming. A master playlist can describe multiple variants, while a media playlist lists playable media segments. When troubleshooting, it helps to identify whether the failing request is the master manifest, a child playlist, or an individual segment.
Practical advice
Use the original source file or URL whenever possible, keep a backup before conversion, and treat browser error messages as troubleshooting signals rather than proof of a specific server-side configuration.