The NBT Changer is MCA Selector’s batch editor: pick chunks, pick fields, and the tool rewrites those fields in every selected chunk in one run. It is how you fix a thousand chunks’ DataVersion, flatten biomes, strip entities or force terrain blending without opening a single chunk by hand — and because it writes straight to disk, it deserves respect.
Back up your world first: MCA Selector writes deletions and NBT changes straight to disk the moment you confirm them — there is no undo and no File → Save step to catch a mistake. Close Minecraft (and stop your server, if the world is on one), then copy the whole world folder somewhere safe before you edit.
What the NBT Changer can change
| Field | What it does |
|---|---|
DataVersion | Rewrites the version stamp of the chunks. It changes the number, not the chunk data format — see the warning below. |
InhabitedTime | Rewrites how long the chunk counts as inhabited — used when preparing chunks for regeneration logic or correcting filter results. |
Biome | Sets the entire chunk to a single biome — the subject of the change biome guide. |
ReplaceBlocks | Replaces one block with another, by name, across all selected chunks. |
DeleteEntities | Removes entities from the selected chunks. |
DeleteSections | Deletes vertical sections (16-block slices) from the chunks. |
FixStatus / FixHeightmaps | Repairs the generation status field / recalculates heightmaps. |
DeleteStructureReference | Removes structure references from the chunks. |
PreventRetrogen | Marks chunks so the game does not try to retro-generate features into them. |
ForceBlend | Forces the terrain blending used at borders between chunks generated by different generators — meaningful mainly around the 1.18 terrain overhaul; on chunks where those conditions do not apply it visibly does nothing. |
RemoveLightingInfo | Strips stored lighting data so the game recalculates it (the field itself was added in MCA Selector 2.9’s update round). |
Compression | Changes how the chunk data is compressed in the region files. |
Custom | A Groovy script that can read and rewrite chunk data with full logic. |
Change vs Force — the two modes
Each field can run in one of two modes. Change only modifies the field where it already exists in the chunk data. Force writes the field even where it is missing. Change is the conservative default: if a chunk does not carry the tag, it is left alone. Reach for Force when you specifically need the value present everywhere — and understand that “everywhere” will then really mean everywhere in your selection. You can also restrict a run to the current selection only, which you should treat as the default discipline: select first, change second, exactly as with the chunk filter.
A safe run, step by step
- Back up the world. Then copy it, and rehearse on the copy.
- Select a small test set — a handful of chunks, not the whole world.
- Open the NBT Changer, set one field only, choose Change mode, limit to the selection.
- Run it, close the tool, and inspect the result: in game, and if you want the raw truth, in the Chunk Editor on one of the edited chunks.
- Only when the test set behaves do you widen the selection to the real target area.
Groovy scripts: power with a blast radius
The Custom option runs a Groovy script against each chunk, giving you programmatic access to the chunk data — the same scripting support the filter dialog offers. Scripts are the way to do things like per-section biome palette edits that the single-value Biome field cannot express. They are also unforgiving: a script bug applies at the same speed as a correct script. Write defensively, test on a copy, and keep the script file with your backup so the change stays reproducible.
The DataVersion warning, plainly
Because DataVersion sits in the field list, it is tempting to “convert” chunks between game versions by renumbering them. Do not. The field is metadata the game uses to decide how to parse and upgrade the chunk; rewriting it does not transform the chunk’s contents. Mismatched DataVersion and content is a reliable route to chunks that fail to load or upgrade wrongly. Legitimate uses exist (repairing a stamp that is genuinely wrong), but version conversion is the game’s job when it loads a chunk, not the NBT Changer’s.
Download MCA Selector 2.9
Everything in this guide works with the current release. Get the Windows installer, the cross-platform .jar, the macOS .dmg or the Linux .deb/.rpm from the MCA Selector download page — every button there points at the official GitHub release files and lists the SHA-256 checksum, with a clearly labelled site mirror as a fallback.
One last backup reminder: keep the copy of your world you made before editing until you have loaded the edited world in Minecraft and confirmed it looks right. Deletions and NBT changes in MCA Selector are permanent once applied.