ModsFinder

Monument Data Fix

by QWERTY770

Monument Data Fix is a library that gives mod authors a way to register custom data fixers, so saves can be upgraded when a mod's data changes.

FabricNeoForgeServer-side onlyMIT LicenseOpen source1.21 – 1.21.5

What it does

Players whose worlds were made with an older version of a data-fixing mod can use Monument Data Fix to upgrade those saves. Authors register their own fixers through the DataFixerRegistry API class, which accepts a name and a fixer and must be called before net.minecraft.util.datafix.DataFixers$addFixers runs. The API is only meant for mod developers; the mod does not document itself as a program for players.

The mod is server-side only, so a server needs it while players join without installing anything. Files are published for Fabric and NeoForge for 1.21 – 1.21.5, under the MIT License and as open source, with source code and an issue tracker linked from the project. Monument Data Fix is required when upgrading saves for a mod that depends on it.

Key features

  1. Custom data fixers

    Authors can register a named data fixer so the game applies it when older saves are loaded.

  2. Registration before startup

    Fixers are added through the DataFixerRegistry API and must be registered before the game adds its own fixers.

  3. Save upgrade support

    Saves made before a mod's data changed can be brought up to date when that mod uses the library.

  4. Public source and issue tracker

    The source code and issue tracker are public, and bugs can be reported there.

Compatibility

Latest build for each game version and loader.

1.21.51.0.01.0.0
1.21.41.0.01.0.0
1.21.31.0.01.0.0
1.21.21.0.01.0.0
1.21.11.0.01.0.0
1.211.0.01.0.0
ReleaseBetaAlphaNot available

Only full game releases are shown. This mod publishes no snapshot builds.

Use cases

Mod developers

Developers whose mod changes stored data can register a fixer so existing worlds keep working after an update.

Server owners upgrading saves

A server owner moving a world to a newer version installs the library on the server so the upgrade runs.

Who it’s for: Mod developers who need data fixers for their own mods, and server owners whose saves depend on a mod that uses this library.

Questions

Does Monument Data Fix need to be installed on clients?

No. It runs on the server alone, so players need nothing extra to join.

Which loaders does Monument Data Fix support?

Files are published for Fabric and NeoForge, with builds for 1.21 – 1.21.5. The latest file for both loaders is 1.0.0 for 1.21.5.

Why is Monument Data Fix required when upgrading saves?

A mod that changes its saved data can depend on it, so the upgrade of older worlds needs this library installed on the server.

In the catalog

Monument Data Fix is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 15,307 mods support Minecraft 1.21.5.

Library mods3,514Fabric modsMods for 1.21.515,307

More from QWERTY770

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Sweet Potato Reborn1.20 – 26.2NBT Data Exporter1.16 – 1.20.1Client Export Helper1.21 – 1.21.11

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What the author says

Note: In Minecraft 1.18.2, Xdi8Aho Mod was a combination of Sweet Potato Mod and the own content of Xdi8Aho Mod. However, Xdi8Aho Mod has already been separated into the two mods, and now Xdi8Aho Mod only contains the content of its own. Therefore, you need to install Xdi8Aho Mod and Sweet Potato Reborn at the same…
QWERTY770, on the Modrinth page

Official listing

Owner
QWERTY770
Published
2025-05-22
Updated on Modrinth
2025-06-12
Facts verified
2026-10-15

Tags

LibraryUtility
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