Just Dance Next is very prone to errors, here are some common errors and how to fix them.
If loading a map keeps loading forever, delete the song's cache folder and recopy the song.
If the video is white, the video file is corrupted, delete the video file and recopy it.
Panda-0008_0101 means that it can't find the cache folder at all for the song,
make sure that the song is in the correct location and that it copied correctly,
DBI sometimes has issues with copying files, so make sure that the files are there.
This can also happen when the cache the song is in is higher or equal to SD_Cache.002A,
this is because the cache is too high and the game can't find it,
to fix this, make sure there are fewer caches.
If all caches are already at max size and can't get bigger, you can try to switch over to exFAT, which can have bigger cache sizes.
Do note that exFAT is more error-prone than FAT32 and can corrupt files more easily and can corrupt the whole drive.
Do this at your own risk as I'm not responsible for any data loss.
Jackrose-0102_0007 means that the song is missing some files,
make sure that the song has all the required files and that they were copied correctly,
again, DBI sometimes has issues with copying files, so make sure that the files are there.