Spotify 3ds Homebrew Fix -

Take the SD card out of your 3DS and insert it into your computer. Create a folder named Music in the root of your SD card. Transfer your exported MP3 or OGG files into this folder. Reinsert the card into your 3DS.

Since the 3DS plays standard MP3 and AAC files natively, many homebrew users do this: spotify 3ds homebrew

The most stable way to listen to music on a 3DS is to use Nintendo 3DS Sound (the official app) or alternative homebrew music players like CTRMus . Take the SD card out of your 3DS