Cannot convert worlds

Might be helpful if such a world save could be downloaded from somewhere for testing (that is, if you have an account in a file sharing service which allows uploading and sharing zip files, upload the zipped world save in there). Without any means to test and not even crash report, it is near impossible to debug an issue like that.

If I'm not totally wrong, I'm pretty sure that theres a crash-reports folder in .minecraft. The crash report might be there, so if you haven't already, check that.

The map was CNB Minecraft's minecart station v1.0 download here http://www.mediafire.com/?zo8gp4z58rakv2y

Confirmed with this world.

Got a NPE in the console:

Jan 18, 2013 9:38:50 PM net.minecraft.server.MinecraftServer b
INFO: Converting map!
Scanning folders...
Total conversion count is 14
t: Reading NBT data
        at bq.f(SourceFile:136)
        at aaz.a(SourceFile:30)
        at ail.a(SourceFile:210)
        at ail.a(SourceFile:181)
        at ail.a(SourceFile:140)
        at net.minecraft.server.MinecraftServer.b(SourceFile:110)
        at bhc.a(SourceFile:54)
        at bhc.c(SourceFile:99)
        at net.minecraft.server.MinecraftServer.run(SourceFile:304)
        at gi.run(SourceFile:565)
Caused by: java.lang.ClassCastException: bx cannot be cast to bz
        at bq.f(SourceFile:134)
        ... 9 more
Jan 18, 2013 9:38:51 PM net.minecraft.server.MinecraftServer run
SEVERE: Encountered an unexpected exception t
t: Reading NBT data
        at bq.f(SourceFile:136)
        at aaz.a(SourceFile:30)
        at ail.a(SourceFile:210)
        at ail.a(SourceFile:181)
        at ail.a(SourceFile:140)
        at net.minecraft.server.MinecraftServer.b(SourceFile:110)
        at bhc.a(SourceFile:54)
        at bhc.c(SourceFile:99)
        at net.minecraft.server.MinecraftServer.run(SourceFile:304)
        at gi.run(SourceFile:565)
Caused by: java.lang.ClassCastException: bx cannot be cast to bz
        at bq.f(SourceFile:134)
        ... 9 more

Jan 18, 2013 9:38:51 PM net.minecraft.server.MinecraftServer run
SEVERE: This crash report has been saved to: C:\Users\user\AppData\Roaming\.minecraft\crash-reports\crash-2
Jan 18, 2013 9:38:51 PM net.minecraft.server.MinecraftServer k
INFO: Stopping server
Jan 18, 2013 9:38:51 PM net.minecraft.server.MinecraftServer k
INFO: Saving players
Jan 18, 2013 9:38:51 PM net.minecraft.server.MinecraftServer k
INFO: Saving worlds
java.lang.NullPointerException
        at net.minecraft.server.MinecraftServer.a(SourceFile:250)
        at net.minecraft.server.MinecraftServer.k(SourceFile:274)
        at bhc.k(SourceFile:219)
        at net.minecraft.server.MinecraftServer.run(SourceFile:362)
        at gi.run(SourceFile:565)

That may be an issue with only this specific world, because the report says:

-- Corrupt NBT tag --
Details:
	Tag type found: INT
	Tag type expected: LONG
	Tag name: LastUpdate
	Tag parent: Level

For convenience attached that world here.

Duplicate of MC-5672.

My world is 240 mb and I still cannot convert it to the new version even after all these bug fixes please tell me how to do it I wanna experience the new version it crashes at 3%

link - https://bugs.mojang.com/browse/MCPE-47427