This happens when a mob is trying to pathfind inside a partially solid block, like a fence post or bed. So far, I've had it happen because a parrot was trying to fly inside a fencepost, a bed, and an alchemy stand. As long as they're sitting this wont happen, but if you have one sitting on the block an alchemy stand is on, for instance, and you let it stand up and try to fly off, the game will crash, and will continue to crash as soon as you load that save.
While this makes your save completely unusable, deleting your entities files like MINABEAN suggests will fix this, because it will delete the entity that was causing the issue; if that entity is an animal that you're trying to keep, it will be gone. I fixed this by using NBTExplorer to edit the position of the entity that caused the error. At worst, you could wait until they patch this.
ParrotsKeepCrashingMyGame
This happens when a mob is trying to pathfind inside a partially solid block, like a fence post or bed. So far, I've had it happen because a parrot was trying to fly inside a fencepost, a bed, and an alchemy stand. As long as they're sitting this wont happen, but if you have one sitting on the block an alchemy stand is on, for instance, and you let it stand up and try to fly off, the game will crash, and will continue to crash as soon as you load that save.
While this makes your save completely unusable, deleting your entities files like MINABEAN suggests will fix this, because it will delete the entity that was causing the issue; if that entity is an animal that you're trying to keep, it will be gone. I fixed this by using NBTExplorer to edit the position of the entity that caused the error. At worst, you could wait until they patch this.