Woalk Datafixer
by woalk
Woalk Datafixer, a Fabric utility, remaps old block, item and biome IDs to new ones when a world loads, using CSV mapping tables.
What it does
Worlds saved under an older Minecraft version can hold block, item and biome IDs that no longer exist after an update. The mod reads two-column CSV files without headers, where each row maps an old ID to a new one, and applies those mappings through the standard Minecraft DataFixer system during loading. A separate block mapping table drives the remapping of BlockItems, and an item mapping table covers plain items.
The mod targets long-running modded multiplayer servers that move to a new version and need to keep items from mods whose names changed or moved to another namespace. When a registry entry is missing altogether, a fallback item is provided instead of an error. Because the data is fixed on load, the remapping must be present on the client and the server alike, and Woalk Datafixer requires Easy Data Fix, Fabric API and Fabric Language Kotlin. It runs on client and server and is published for 26.2 only, under the GNU General Public License v3.0 or later, so the source code and issue tracker are public.
Key features
CSV mapping tables
Replacements are listed in simple two-column CSV files, one mapping per row, with no header line to write.
Block and item remapping
Separate block and item tables let the server map each old identifier to the new one it should become.
Biome ID remapping
Old biome identifiers are swapped for new ones as the world loads, so saved chunks keep their intended biomes.
Fallback for missing entries
Registry entries that no longer exist are replaced with a fallback item, so the world still loads.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 3
Use cases
Who it’s for: Server owners running modded multiplayer worlds through a version update, and modpack authors who need old identifiers to keep working after a change.
How it compares
Vanilla Tweaks Data Fixer is server-side only, open source under the MIT License, and published for Fabric at 1.20.6 – 1.21, so players need nothing installed. Configurable Everything is open source under the GNU General Public License v3.0 only, runs on Fabric and Quilt for 1.20.1 – 26.1.2, and is optional on either side. Woalk Datafixer is client and server, open source under the GNU General Public License v3.0 or later, and published for Fabric at 26.2 only.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Woalk Datafixer | Fabric | 26.2 | Client and server | 2026-09-12 |
| Vanilla Tweaks Data Fixer | Fabric | 1.20.6 – 1.21 | Server-side only | 2024-07-02 |
| Configurable Everything | Fabric and Quilt | 1.20.1 – 26.1.2 | Client or server, optional | 2026-03-24 |
Questions
Does Woalk Datafixer need Easy Data Fix?
Does the mod have to be installed on the client?
Which Minecraft versions does Woalk Datafixer support?
In the catalog
Woalk Datafixer is one of 36,990 Utility mods on ModsFinder, and one of 25,772 Utility mods for Fabric. 13,894 mods support Minecraft 26.2.
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What the author says
Woalk Datafixer is a Fabric mod designed to handle missing or changed blocks, items, and biomes when loading Minecraft worlds. It allows for seamless remapping of registry entries using CSV mapping tables and provides a fallback for items that are completely missing from the registries. This mod is designed for…
Official listing
- Modrinth page
- modrinth.com/mod/woalk-datafixer
- Owner
- woalk
- Published
- 2026-08-08
- Updated on Modrinth
- 2026-09-12
- Facts verified
- 2026-10-15