I wanted to check out an old creative world me and my friends used to play on. When I load the world in 1.8.9 (the version I think the world was using), it just drops me into a void and I can't do anything. Commands don't work and trying to save and quit just freezes Minecraft. Then I tried loading it in 1.14.4, where a bit of the world actually works and I can fly around to look at the spawn area, but other than that I can't do anything.
EDIT: The only notable thing I could find in the console was "Command Block chain tried to execute more than 0 steps!" a bunch of times.
EDIT 2: I fixed the above console line by setting maxCommandChainLength to 100 via NBTExplorer. Still didn't fix the overall issue.