ErrorLib
by Unknown_303
ErrorLib is a Forge library by Unknown_303 that gives other mod developers ready-made building blocks for custom content.
What it does
ErrorLib serves as a core API for mods made by Unknown_303 and by other developers who choose to use it. Its code covers custom horse armor, custom armor trim patterns and materials, custom abilities, custom tool tiers and a custom IForgeRegistry, so a developer can reuse these parts instead of writing them from scratch. The library also includes content of its own, such as Corrupted Heart and Corrupted Forge, and supports crafting recipes that use silver, tin, steel, titanium and other materials.
The library runs on client and server, so both the server and every player need it. Files are published for Forge only, with 1114 library mods in the catalog that also target 1.20.1. The latest file is 2.1.2-1.20.1, released on 2025-10-13, and the code is open source under the GNU General Public License v3.0 only. The first release came on 2024-10-16.
Key features
Custom horse armor
Developers can register horse armor types through the library, with the armor appearing on horses in the world.
Custom armor trim patterns
The library lets developers define new armor trim patterns and the materials they apply to.
Custom tool tiers and abilities
Custom tool tiers and special abilities can be defined for tools and armor built on the library.
Custom registry support
A custom IForgeRegistry is provided so mods can register their own content types in a consistent way.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Building new materials
A mod that adds silver, tin, steel or titanium tools and armor can use the library's tool tier and material code.
Who it’s for: Mod developers who want shared API code for horse armor, trim patterns, tool tiers or registries, and players who run mods built on ErrorLib.
How it compares
Memory Foam is server-side only, open source under the MIT License and published for Forge 1.20.1, so only the server needs it. CreateFirmaCraft - Core is also Forge 1.20.1 and runs on client and server, but it is not open source and is released under the MIT License. For Armor Purposes is a Forge 1.20.1 mod that runs on client and server and is released under All rights reserved, so its code is not open for reuse. Connectorlib is client-side only and open source under the Apache License 2.0, and it covers Fabric, Forge and Quilt for 1.20 – 1.20.6.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| ErrorLib | Forge | 1.20.1 | Client and server | 2025-10-13 |
| Memory Foam | Forge | 1.20.1 | Server-side only | 2025-09-27 |
| CreateFirmaCraft - Core | Forge | 1.20.1 | Client and server | 2025-12-01 |
| For Armor Purposes | Forge | 1.20.1 | Client and server | 2025-09-01 |
| Connectorlib | Fabric, Forge and Quilt | 1.20 – 1.20.6 | Client-side only | 2025-08-04 |
Questions
Does ErrorLib need to be installed on the server?
Which loader does ErrorLib support?
Can a developer change ErrorLib's code?
In the catalog
ErrorLib is one of 3,514 Library mods on ModsFinder, and one of 1,576 Library mods for Forge. 34,764 mods support Minecraft 1.20.1.
More from Unknown_303
Similar mods
What the author says
In game, ErrorLib adds the Corrupted Heart and Corrupted Forge (not yet added) and other api services for developers. For developers, it speeds up the process of implementing certain features, and makes it easier to implement features that have no tutorials for 1.20.1. It would also be very helpful if you could…
Official listing
- Modrinth page
- modrinth.com/mod/errorlib-api
- Owner
- Unknown_303
- Published
- 2024-10-16
- Updated on Modrinth
- 2025-10-13
- Facts verified
- 2026-10-15