Copper Age Backport Duplicate Copper Armor Material Fix
by cyroinferno1
The addon stops a crash that occurs when two copper armor materials are registered at once in the backport, so the copper armor set loads cleanly.
What it does
The addon targets a crash players hit in Copper Age when the duplicate copper armor material was registered twice. It requires Copper Age Backport, which adds the copper armor pieces in the first place. Without this fix, a world loading both sets can fail at startup.
The mod is a small patch and does not add new blocks, items or menus. Its only job is to remove the duplicate material so that copper armor from the backport loads cleanly alongside the rest of the modpack. Files target 1.21.1 alone and are published for NeoForge.
Both sides of a connection need the addon, since the material registration happens on the server and the client alike. The code is released under the MIT License, and the project is not open source, so changes are limited to what the author publishes.
Key features
Duplicate material removal
The addon removes the second registration of the copper armor material, so only one definition is loaded.
Crash prevention
Worlds that contain both copper armor sets no longer fail at startup because of the repeated material.
Backport companion
The fix is written for Copper Age Backport and is meant to run next to it, not on its own.
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 1
Use cases
Modpacks with copper armor
Pack makers who combine Copper Age Backport with other armor mods can add this fix to avoid the startup error.
Who it’s for: Players and server owners running Copper Age Backport on NeoForge 1.21.1 who see a crash tied to duplicate copper armor material. The addon is not needed when the backport is not installed.
How it compares
Copper Age Backport Durability Fix is another addon for the same backport, but it covers Fabric and NeoForge with the MIT License and targets only 1.21.1. More Gear Types is a NeoForge-only mod under the Apache License 2.0 that also targets 1.21.1, but it adds new gear instead of fixing a crash.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Copper Age Backport Duplicate Copper Armor Material Fix | NeoForge | 1.21.1 | Client and server | 2026-09-11 |
| Copper Age Backport Durability Fix | Fabric and NeoForge | 1.21.1 | Client and server | 2026-05-17 |
| More Gear Types | NeoForge | 1.21.1 | Client and server | 2026-06-25 |
Questions
Does this addon require another mod?
Does the fix need to be installed on both sides?
Which loader and version does the fix support?
What the author says
A small addon mod that fixes duplicate Copper armor material crash experienced when Copper Age Backport is installed with other mods that add copper armor.
Official listing
- Owner
- cyroinferno1
- Published
- 2026-09-11
- Updated on Modrinth
- 2026-09-11
- Facts verified
- 2026-10-15