> For the complete documentation index, see [llms.txt](https://docs.onelitefeather.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.onelitefeather.net/falco/reference/supported-versions.md). # Supported versions The versions Falco is built against, the versions it accepts, and the floors it refuses below. > **This page is a generation target, currently written by hand.** Source of truth: the version catalog and Java toolchain in the [Falco build](https://github.com/OneLiteFeatherNET/Falco), and the constants in [`FalcoAnvilLoader`](https://github.com/OneLiteFeatherNET/Falco/blob/main/falco-anvil/src/main/java/net/onelitefeather/falco/anvil/FalcoAnvilLoader.java). ## Build and runtime | | Value | Note | | -------- | ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | Java | 25 | required to build Falco and to run it | | Minestom | `2026.10.07-26.2` | resolved through `net.onelitefeather:mycelium-bom` `1.8.9` (`settings.gradle.kts`, `mycelium-bom` `version("bom", "1.8.9")`); `compileOnly`, so a consumer picks its own | ## Chunk data version floor | | | | ------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Constant | [`FalcoAnvilLoader.DEFAULT_MINIMUM_DATA_VERSION`](https://github.com/OneLiteFeatherNET/Falco/blob/main/falco-anvil/src/main/java/net/onelitefeather/falco/anvil/FalcoAnvilLoader.java) | | Value | `2844` | | Corresponds to | Minecraft snapshot `21w43a` | | Builder slot (read side) | `minimumDataVersion(int)` | | Builder slot (write side) | `dataVersion(int)` — stamped into every saved chunk; unrelated to the floor | | Enforced by | `ChunkVersionPolicy`, by default `DefaultChunkVersionPolicy` | `21w43a` is where a chunk's data moved out of the `Level` compound onto the root compound, under the key `sections` (`FalcoAnvilLoader.SECTIONS_KEY`, a `private` constant, so it is not linkable). ### What the guard does with each case | Stored state | Result | | ------------------------------------------------------------ | ---------------------------------------------------------- | | No `sections`, but a `Level` compound | refused — pre-`21w43a` layout, whatever `DataVersion` says | | Current layout, `DataVersion` absent | accepted | | Current layout, `DataVersion` wrong type | refused | | Current layout, `DataVersion` negative | refused | | Current layout, `DataVersion` below the floor | refused | | Current layout, `DataVersion` at or above the floor | accepted | | `Status: minecraft:full` with neither `sections` nor `Level` | refused, `MISSING_OR_MISTYPED_KEY` | | Current layout, empty `sections` list | accepted | ## Compression schemes | Id | Scheme | Read | Write | | --- | ------------ | ---- | ------------ | | 1 | gzip | yes | no | | 2 | zlib | yes | yes — always | | 3 | uncompressed | yes | no | | 4 | LZ4 | no | no | | 127 | custom | no | no | The external bit `0x80` is masked off. Any other id raises `The compression scheme is not supported. Only gzip (1), zlib (2) and none (3) can be read` ([`ChunkCompression#fromId`](https://github.com/OneLiteFeatherNET/Falco/blob/main/falco-anvil/src/main/java/net/onelitefeather/falco/anvil/ChunkCompression.java)). ## World directory layout | Layout | Path resolved from the world root | | -------------- | ------------------------------------------------------------ | | 26.1 and later | `worldRoot/dimensions///region` | | pre-26.1 | `worldRoot/region` — used only when the above does not exist | ## Artefact availability `falco-bom` is not served for releases before `1.0.0`: it was added after `0.3.0` was cut. A 404 for `falco-bom` at a version below `1.0.0` is therefore expected, and the modules of those releases are declared with their own versions. `falco-migration` is not in the BOM. See [Reference Modules and coordinates](/falco/reference/modules-and-coordinates.md) for every coordinate. Related: [Explanation The chunk version guard](/falco/explanation/the-chunk-version-guard.md) · [How-to Migrate a world from an older version](/falco/how-to-guides/migrate-a-world-from-an-older-version.md) · [Reference Modules and coordinates](/falco/reference/modules-and-coordinates.md) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. 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