I store my music on an external drive. My hard drive space is too limited to have my entire collection on it when I have a good sized external drive. I've set Spotify's cache (where offline music is stored) to that external drive. That works fine. However, if I start Spotify without my external drive plugged in, rather than saying that Spotify couldn't find the music and to please mount the drive or listen to music via streaming, Spotify starts redownloading all the music that I set to offline and changes the cache location back to the local drive. Even if I then plug my external drive in, it has to redownload all the offline music. This isn't convenient when I have 2,000 offline tracks. That takes a while to download.
I would like Spotify to recognize that my external drive isn't mounted and then say: you'll be unable to listen to your offline music. Then pause any syncing until my external drive is plugged back in (and look for the tracks when it gets plugged back in rather than starting syncing all over when all the tracks are still on the external drive).
I'm sure I can't be the only person that would like to store their music on an external drive. As it is right now I'm forced to make sure I have my external drive with me wherever I go or not open Spotify on my laptop (because if I do it will have to resync EVERYTHING, even once I plug my drive back in).
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