This appears no matter what I do. I have tried every single previous version of this, reinstalled it again and again, nothing works.
If any of this matters:
The mp3 is in the downloads folder (I have tried it in the folder the exe is in too)
I have changed zero settings in the exe itself.

Same issue.

Seem to get this error even in the newest version. Seems to happen when the files are already .ogg files. Haven't fully tested this yet using .mp3 instead, will update this thread when I have more info.

It worked fine before until I checked "Play tracks from jukebox block"

Update: This issue only exists when the "Play tracks from jukebox block" is active or any other "convert to .ogg" is active

(currently using version 1.8.0)

Facing the same issue here, however if you convert them into .ogg yourself it works.