I was playing normally when my computer said to restart for updates, so I saved and excited my game, which was in 1.8.1. my computer restarted and updated, and when I opened my world back up I was in the same place, but completely missing my inventory, and now playing 1.7.4. I died, and when i re spawned in my house, everything was gone in all of my chests. I had chickens, cows, sheep and pigs in a pen, those are all still there, but my dogs aren't
UPDATE: this has happened in every world but 1
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Dupe of MC-45009.
Downgrading is not officially supported.