https://techcrunch.com/2017/12/20/amazon-music-to-end-support-for-streaming-your-uploaded-mp3s/

In the early days of streaming music services, some aimed to differentiate themselves by offering users the ability to upload their personal collection of MP3’s, which could be streamed alongside the on-demand streams and radio stations offered by the music service itself. Rdio, which later sold to Pandora, offered music uploads for matching purposes, for example. Amazon Music, meanwhile, let you upload your own songs from your Mac or PC. But no more. Amazon quietly announced this week it’s retiring its Amazon Music Storage subscription plans, with plans to completely disallow playing or downloading songs from the service starting in January 2019.

The shutdown was first spotted by Slashgear, which pointed to new help documentation on Amazon’s website.