Realms world upload error: "Cannot invoke "ctt.c()" because "this.b" is null"

Should be listed as affects version 1.20.3.

Please try and upload a newly created vanilla world and see if you get the same error

@Greymagic27 Confirmed. Made the description more specific.

This can be reproduced if any of the world 1) is a symlink not authorized or 2) has corrupt level.dat.

Code analysis (1.20.4 yarn)

RealmsSelectFileToUploadScreen has multiple LevelSummary#isHardcore calls. This is defined as this.levelInfo.isHardcore();.

LevelSummary has multiple subclasses, including SymlinkLevelSummary and RecoveryWarning. They are "fake entries" that aren't loaded. Hence, levelInfo == null. However, they do not override isHardcore, so any call to that method would throw NPE as seen here.

LevelStorage#loadSummaries, used to enumerate the worlds, does not filter those 2 special cases, either (they are also used by the regular world screen, which needs to list those). And since the world enumeration and isHardcore calls occur when rendering RealmsSelectFileToUploadScreen, this error occurs.

Hello i have the same problem in 1.20.4. I cannot reset and load a world from the current 1.20.4 world we play on and not from a different reset world. I can reset the world with the ''World templates'', ''New World'', Adventures'', ''Experiences'' and ''Inspiration'' butten, only not ''Upload world''.

This is the error is get:

Maybe its a little hard to read due to my texture pack but it says:

Cannot invoke ''net.minecraft.class_1940.method_8583()'' beceus ''this.fiels_25022'' is null

Can confirm Helboy234's comment. I am unable to post a modified world onto my realm, and clicking Upload World gives me this:

having same issue how do i fix

This will be fixed in the upcoming release 1.20.5. There's no release date for it yet, but it's currently in the pre-release phase, which means it'll be commonly available soon.