From Linux. Demonstrates the issue with a Minecraft generated world map using the steps outlined in bug report MC-46082.
I can confirm that the above steps will produce a situation which causes Vanilla Minecraft to hang (running on Minecraft Linux):
[code][10:51:53 INFO]: Client> [10:51:53] [Server thread/INFO]: Starting integrated minecraft server version 1.7.4
[10:51:53 INFO]: Client> [10:51:53] [Server thread/INFO]: Generating keypair
[10:51:54 INFO]: Client> [10:51:54] [Server thread/INFO]: Converting map!
[10:51:54 INFO]: Client> [10:51:54] [Server thread/INFO]: Scanning folders...
[10:51:54 INFO]: Client> [10:51:54] [Server thread/INFO]: Total conversion count is 0
[10:51:54 INFO]: Client> [10:51:54] [Server thread/ERROR]: Encountered an unexpected exception
[10:51:54 INFO]: Client> s: Exception getting block type in world
[10:51:54 INFO]: Client> at afs.<init>(SourceFile:202) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at mm.<init>(SourceFile:69) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at btk.a(SourceFile:70) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at btk.e(SourceFile:99) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at net.minecraft.server.MinecraftServer.run(SourceFile:327) [1.7.4.jar:?]
[10:51:54 INFO]: Client> at lb.run(SourceFile:616) [1.7.4.jar:?]
[10:51:54 INFO]: Client> Caused by: java.lang.IllegalArgumentException: bound must be positive
[10:51:54 INFO]: Client> at java.util.Random.nextInt(Random.java:388) ~[?:1.8.0]
[10:51:54 INFO]: Client> at agr.a(SourceFile:122) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at agr.a(SourceFile:27) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at agl.a(SourceFile:364) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at ahg.a(SourceFile:74) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at apl.a(SourceFile:162) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at ml.a(SourceFile:160) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at aoo.a(SourceFile:778) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at ml.c(SourceFile:95) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at ml.d(SourceFile:108) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at afs.e(SourceFile:311) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at afs.a(SourceFile:249) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at afs.c(SourceFile:273) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at afs.b(SourceFile:234) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at apf.a(SourceFile:62) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at mm.b(SourceFile:565) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at mm.a(SourceFile:534) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at afs.<init>(SourceFile:193) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> ... 5 more
[10:51:54 INFO]: Client> [10:51:54] [Server thread/ERROR]: This crash report has been saved to: /home/seann/.minecraft/crash-reports/crash-2014-02-22_10.51.54-server.txt
[10:51:54 INFO]: Client> [10:51:54] [Server thread/INFO]: Stopping server
[10:51:54 INFO]: Client> [10:51:54] [Server thread/INFO]: Saving players
[10:51:54 INFO]: Client> [10:51:54] [Server thread/INFO]: Saving worlds
[10:51:54 INFO]: Client> [10:51:54] [Server thread/ERROR]: Exception stopping the server
[10:51:54 INFO]: Client> java.lang.NullPointerException
[10:51:54 INFO]: Client> at net.minecraft.server.MinecraftServer.n(SourceFile:299) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at btk.n(SourceFile:230) ~[1.7.4.jar:?]
[10:51:54 INFO]: Client> at net.minecraft.server.MinecraftServer.run(SourceFile:389) [1.7.4.jar:?]
[10:51:54 INFO]: Client> at lb.run(SourceFile:616) [1.7.4.jar:?]
Full log file attached.
I'm getting this error with Java Minecraft on Linux, so the proposed solutions above won't work because unless I create a Lutris instance or a WINE bottle, and run the Windows version through these extra steps, I can't make use of these XBox add-ons. To make matters more complicated, I'm running Minecraft on two systems - both Linux, both fully updated, and it works fine on one using the native Linux launcher without all these extra XBox things, but not the other, and when I try to add the account from the failing one to the good one, it gives me the pre-migration Mojang username, and restricts me to the demo version.
Edit **
I'm able to add my Minecraft account to the computer that's getting this error, and it works just fine - I can play all available versions on my profile but when I switch back the one getting the error, I get the error again, and I'm limited to the demo. I remember now why I stopped using Microsoft stuff after they bought and ruined Hotmail.
Edit 2 **
I tested my wife's Java Edition, because she's on Windows 7 still, and hers works just fine. Likewise, I was able to add my account to her machine, and my account worked fine. Still no extra XBox apps required (they say they need minimum Windows 10 to run anyway). But again, when I tried to add our kid's account, I get the error, I'm limited to the demo version, and it's just the pre-migration account showing. So now I'm thinking there's something wrong on Microsoft's end and it's not a "user didn't install something" error because I've demonstrated now on three computers that these extra XBox apps aren't strictly needed for my OSes.