Old Forge mods, unmodified, in a modern game.

History

Mods in this run

How it works

Compatibility is determined by running Legacy Connector's translation on the mod jar and validating the result. This runs outside of the game with the checkLegacyMod tool (tools/compat/probe.py); all jars of a run are translated as one mod set, so a mod and the library or parent mod it builds on can find each other.

The categories. Ready to test: the mod translates and everything it uses exists, so it is worth trying in game. Partly placeholder: it translates, but 10 or more features it uses are empty placeholders, so large parts probably do nothing. Missing game features: it needs old Minecraft or Forge functionality (or an API the layer provides itself, such as NEI) that we have not built yet; this is our work to do. Needs another mod: it depends on code from another mod, such as Thaumcraft, IC2 or AE2, that is not available or does not match the version it expects. Needs removed code: it uses old Java or library code that no longer exists. Not needed: 1.7.10 and 1.12.2 engine patches (performance, bug fixes, ID extenders) with nothing to do on 1.21.1.

Resource check. The same run also checks every translated mod's models, blockstates and textures for references that point at nothing (the usual start of a purple-and-black texture or an invisible block), without starting the game. It separates references the translation lost from ones the mod never shipped itself. It cannot judge what anything looks like.

"Ready to test" does not mean "works". The game is never started: this only shows the jar translates and nothing it uses is missing. Startup problems, bad assumptions about world generation, rendering, or runtime-only failures only show when the game runs, and some unresolved references sit in code paths a mod never reaches. For in-game results see the mod list, where player reports and in-game tests outrank this probe.

The jars come from Modrinth's most downloaded Forge mods and are discarded after the run. If a result is wrong, open a compatibility report.

Vanilla files mods expect that 1.21.1 does not have

Files of the original game that 1.12 and 1.7 mods name directly (a model template, a texture) and that Minecraft renamed or removed. They are the layer's to supply or rename, and each one fixes every mod in its row at once. Sorted by how many mods need it.

Mods

Lost in translation: the mod's own jar ships the file (or it is a vanilla file), but it is not there after translation, so the layer should fix it. Mod's own: no jar of the mod ships it, so 1.12 showed it missing too; nothing for the layer to do, but it explains purple textures that are not our fault. References into the namespace of a mod that is not in the test set are ignored.

1. Start the game once with the mod installed; Legacy Connector writes logs/legacyconnector-report.txt.
2. Press Report a mod (or Report this mod on a mod in the list). It opens a GitHub issue form with the mod name filled in.
3. Pick the result, describe what you tried, attach the report file, and submit. The list updates within a few minutes of your submission.

You need a free GitHub account. Please don't attach mod jars, only logs and screenshots.

Report a mod All reports