If you own this game or even if you just own a Wii or a Wii U and a Wiimote you might want to download this free patcher just in case you end up with a copy of the game or resell your console.

The channel is free and it doesn't prevent the glitch as far as I know, it just fixes the issue if it happens. The glitch happens if you talk to an NPC a second time after finishing a dungeon, doing this will prevent the game from progressing and you have to start over or patch it to finish the game.

More info: https://zelda.gamepedia.com/The_Legend_of_Zelda:_Skyward_Sword_Save_Data_Update_Channel
http://en-americas-support.nintendo.com/app/answers/detail/a_id/2939/~/the-legend-of-zelda%3A-skyward-sword-%E2%80%93-song-of-the-hero-quest-issue