Clarification note
This bug seems to be caused by a JVM bug:
We've identified the big 1.13-pre4 crash as a bug in Java itself! We have a fix lined up, but it's always exciting to be reminded that the JRE isn't infallible.
The bug
When creating a new world on 1.13-pre4, the first time I loaded up a new world, the game hung up on the "loading world" screen. The second time, it loaded 25% of the spawn area. Closing the game and loading the world progresses the "preparing the spawn area" screen between zero and four percent each time. After ten times attempting to load a new world, I'm at 36%.
Related issues
is duplicated by
Attachments
Comments


It looks like something's broken in world generation.
I created two new worlds in SinglePlayer.
random seed
seed = "1.13-pre4"
In both cases MC stops running somewhere during loading the save game. {screenshots: taskmgr, loading screen}
Loading (a copy of) a save created in pre3 works OK.

However, joining servers still function correctly, i ran a test on it.

Exactly the same issue for me too, when creating a new world.

Duplicate of MC-132069 unless it is not reopened.

Happens to me as well. Odd.
Edit: ...and why do the most important things always break? How did they not notice this major bug sooner? Oh well. Back to 12.2 for now.

Also happens to me. But also, I was unable to load a fresh world created today in 1.12.2. Didn't have any worlds created in the other pre-releases or snapshots to test (I always delete worlds made in snapshots when a new snapshot comes out.)

How many times has Mojang broke the game so far? Just wondering.

The crash log states that an IllegalStateException occurred. Could this be useful somehow?

Was able to create a world in 1.13 pre-release 3 and load it in 1.13 pre-release 4 without issues.

Indeed, opening a 1.13-pre3 world in 1.13-pre4 works fine (and opening that converted world later works, too), while creating a new 1.13-pre4 world freezes at "Loading world". Opening a 1.12.2 world freezes at "Prepare spawn area 1%".

Can confirm. I can't create a new world in 1.13-pre4.

Also unable to load worlds generated in 1.12.2
Stuck at the "Loading World" screen.
Also worth noting that world generation has slowed down considerably since earlier snapshots.

At least we can create superflat world

Confirmed (At least for singleplayer) - Creating a world in pre4 does not work. Opening a created pre3 world does work well.
Creating a Superflat World DOES work for me in pre4.
Creating a DEAFULT or LARGE BIOMES world does not work

Same problem for me, singleplayer survival world does not load. (Minecraft version 1.13 pre4) But any pre3 world will load perfectly.

this is happening for windows 7(64bit)/java 1.8.0-171 b11 home as well

Same issue, with the same error pre4. Will test a superflat world
However my world does not load at all. It just crashes over and over.
Edit: After 4 consecutive attempts at loading the same world, it has started to actually prepare spawn area before crashing, causing the game to freeze and require task manager to terminate the process.
*Edit: Successfully loaded world. Though there was a very strange, loud sound made by the game as I joined the world. Sounds like I'm listening to someone on the phone while they are in a tunnel with a train.
The lag is still there just like previous snapshots. Possibly even worse than before.

Please edit / comment with care, it sends an email update to everyone each time you do so.

Same issue when trying to create a new 1.13 Pre4 singleplayer game. I am running Windows 10.

Can confirm in 1.13-pre5.
However, when the integrated server crashes the client closes too (part of working on a fix?). Anyway, my crash report seemed to have more information attached to it so I posted it to the image.

appear to be fixed in 1.13-pre5 ,you can now create default world and large biomes

@unknown, @unknown:
Can confirm in 1.13-pre5.
appear to be fixed in 1.13-pre5
Hm.

Works for me in pre5

Look at the crash report I posted from pre5. It still happens for me (although admittedly not every time–at the time I wrote the comment it was the first time I attempted generating a new world), not to mention that it wasn't marked as 'fixed' yet by Mojang.

We have two computers each with their own Minecraft account. One is able to start a new world as of today but the other is not. Both had the same problem as described yesterday and both are now on Pre5. One of them can create a world now but the other appears to still have the same problem. I'm currently in the middle of formatting the other PC with a fresh windows install (unrelated) and we'll see if it continues to have problems.

Just figured it out–this is a Java related issue. Running 1.8.0_25 (which was the version I ran in the first crash that came from the launcher) caused it to crash the game. Running an updated version which I got since then gave me no issues.
Sorry for any confusion.
EDIT: Dinnerbone on Twitter
EDIT 2: I'm pretty sure today's update to the launcher changed the built-in Java version (1.8.0_51), and fixed the issue for me..

Fixed with Launcher versions 2.1.1216 / 2.1.1217 / 2.1.1218 and the updated bundled JRE 1.8.0_51

The crash is still present in 18w43c, just occured a few times while generating chunks in a new singleplayer world. Not sure how to reproduce it consistently yet.
[media][media]OS: Windows 10 1803 (Build 17134.112)
Java: Bundled JRE (1.8.0_51)
JVM Arguments: Default + -Xms4G -Xmx4G

I have been having the issue in 18w43c as well. So far, all I've done in the version is fly around the world a lot, but the world continually fails to load in, freezing and loading a few chunks, then freezing and loading a few more, and every once in a while freezing and then loading in everything around me as expected. It continues this cycle regularly until eventually, around the time when I'd expect the world to load everything normally, the entire game simply crashes.
[media]
Edit: I tried running in Java 11 as well just to see if that would fix anything, but it didn't.

This crash is still present in 18w44a. I just experienced it on the first launch of a 1.13.1 world in 18w44a within minutes of the world version upgrade. I have attached my crash report (
[media]) that was generated after the crash. The crash occurred when I died and attempted to load the spawn chunks at a custom location set a couple thousand blocks from spawn- the world refused to render and within 30 seconds the game crashed. I have tried for hours to reproduce this crash, to no avail.
The crash report in 18w44a is identical to the ones posted by VideoklipBG (
[media]and
[media]). Although the file names are different, this is because of the obfuscation between versions since the line numbers match up perfectly. The line numbers in mine are all off a bit from the original crash reports.
The only thing that caught my eye when I was comparing the crash reports here was that mine referenced datafixer in one of the last few lines in the stacktrace. This led me to think that this was caused (and thus reproducible) by converting another 1.13.1 world. This does not seem to be the case at the moment.