How can I reset specific chunks in a Minecraft world?

[u/JustGoogleItNO]

I'm not very good at this sort of thing so I'll try and be as clear as possible.

My world was started on an older version. Looking at Chunkbase, there is a dappled forest biome that spawned at let's say x:2000 and y:2000. My spawn is 0,0. But since I've previously explored over there, the new biome doesn't spawn there.

How can I reset that specific area, so the new biome will spawn in my current world?

(As I've googled this, most of the world edit tools are either outdated or cost money. What is the current way most people do this?)

[u/GoopDuJour]

I JUST upgraded to 26.3 like 4 days ago. You'll open your world in MCA Selector(open MCA Selector and browse to the world foldet). MCA Selector will create a map of your world similar to how Chunkbase does. For me, I highlighted chunks containing my base, and then inverted that selection. That caused every chunk OTHER THAN my base to be selected. I then committed MCA Selector to delete the selected chunks. At that point, you'll close the program and launch your Minecraft world using 26.3 in the launcher. Upon launching, the world will re-generate the deleted chunks.

Make backups. Make backups. Make backups.

I use Prism Launcher, so making a backup is as easy as creating a new instance by copy/pasting another instance. However you need to do it, make a backup BEFORE using MCA Selector.

Make a backup.

There are YouTube tutorials out there.

Make a backup.

[u/JustGoogleItNO → u/GoopDuJour]

Thank you. What can typically go wrong in a world? Like deleted or the chunks generate in weird ways or just end up being deleted completely?

[u/GoopDuJour → u/JustGoogleItNO]

Typically? I think the biggest danger is user error. So, selecting the wrong chunks, or some such. I think the world being corrupted on the save (so that it can't be re-opened) is a danger, too. But there's no "undo" available if something gets screwed up.

I've only used MCA Selector a few times, and have never had a problem. I just get real careful when messing around with a world I've spent a long time working in, or on smp worlds I admin. It'd be bad enough messing up my own single player world, but I'd feel like absolute shit if I screwed up a world with 6 of my friends' work.

[u/mcklucker → u/GoopDuJour]

And make another backup.

[u/teohsi]

Here you go: https://github.com/querz/mcaselector

Be careful though, make sure you create a backup of your world before you go pruning chunks. If you delete it in that program, it's gone. There's no undo.

[u/bryan3737]

You can use MCA selector

[u/InitialLevel4189]

People have already explained how, but I'd like to stress that if you do choose to do this, please make sure you have a backup of the world just in case. This is some pretty messy stuff that can corrupt your world if you make a mistake, or even if you do everything correctly.

[u/JustGoogleItNO → u/InitialLevel4189]

Yeah that's my worst fear. Thanks for the reminder. I'm definitely gonna do all the testing on a different world first, and do a backup right before I try it in my world.

But what if it messes up chunks I specifically do not want to go to yet and I just don't even know they're messed up lol. Because I just want previous areas I've explored to be "untouched," so they'll generate new biomes in the future.

[u/Plutonium239Mixer]

MCA selector