Ben Knepper

This is happening to me every time I try to save and quit on a LAN session as well. I've only noticed this error this last time, so I'm not sure if it's happened every time, but I got the same error as this report MCL-1905. Here's the error report in the Launcher Log (there's no sign of an error in Game Output) (11:48 is when I launched the game, and 13:58 is when I tried to quit):

[11:48:53 FATAL]: Fatal error launching game. Report this to http://bugs.mojang.com please!
java.io.FileNotFoundException: File 'C:\Users\Ben\AppData\Roaming\.minecraft\assets\indexes\legacy.json' does not exist
	at org.apache.commons.io.FileUtils.openInputStream(FileUtils.java:299) ~[launcher.jar:?]
	at org.apache.commons.io.FileUtils.readFileToString(FileUtils.java:1711) ~[launcher.jar:?]
	at net.minecraft.launcher.Launcher.cleanupOrphanedAssets(Launcher.java:252) ~[launcher.jar:?]
	at net.minecraft.launcher.Launcher.performCleanups(Launcher.java:494) ~[launcher.jar:?]
	at net.minecraft.launcher.game.MinecraftGameRunner.launchGame(MinecraftGameRunner.java:221) ~[launcher.jar:?]
	at com.mojang.launcher.game.runner.AbstractGameRunner.onDownloadJobFinished(AbstractGameRunner.java:185) [launcher.jar:?]
	at com.mojang.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:122) [launcher.jar:?]
	at com.mojang.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:12) [launcher.jar:?]
	at com.mojang.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:86) [launcher.jar:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_65]
	at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_65]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.7.0_65]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.7.0_65]
	at java.lang.Thread.run(Unknown Source) [?:1.7.0_65]
[13:58:05 ERROR]: Game ended with bad state (exit code -805306369)
[13:58:09 INFO]: Ignoring visibility rule and showing launcher due to a game crash
[13:58:12 INFO]: Deleting C:\Users\Ben\AppData\Roaming\.minecraft\versions\1.8.1\1.8.1-natives-296251035682913

Edit: My next time hosting a LAN world it happened again with the same error.

Before I reported this, I did see how high I could build on a normal world to make sure I was remembering correctly, and could only get up to y=255. I thought that was always the case.

Okay. Well either way, it is above the building limit. Breaking one of the highest blocks and trying to replace it is impossible, while it is possible two blocks down. Also, Caver's Delight only goes to 255 (or 254), as shown by cut off trees.