Fabric Wiki

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:!: //This page is irrelevant, most mods are now on Loader 0.4.x, and should be removed from the sidebar and kept archived for miscellaneous use.//

====== Loader 0.4.x and You! ======

This tutorial lists what you need to know to update your mods to **Loader 0.4.x** (and beyond!?).

===== Schema changes =====

The schema has changed somewhat. Throughout 0.4.x, the schemaVersion 0 will be supported, but no such promises are made for 0.5.x and beyond.

Useful sources:

  * [[documentation:fabric_mod_json|fabric.mod.json format]]
  * [[https://github.com/FabricMC/fabric-example-mod/|Example mod]], which should be updated by now ([[https://github.com/FabricMC/fabric-example-mod/commit/d6e85e22192c7d824572668f54a5bf81eec3bc78|update commit]])
===== Nested JARs =====

{{:tutorial:nested_jar.png?direct|}}

There has been a lot of confusion about what nested JARs are meant to be used for.

Nested JARs **are**:

  * a solution to provide dependencies which are in the form of //Fabric mods//, allowing the loader to pick the best version matching a given modpack's sets of dependencies,
  * a solution that allows you turning libraries into //Fabric mods// and avoiding conflicts where they are not cleanly shadowable or where there is good reason for a Fabric mod developer to be the authoritative versioning source,
  * a potential solution to cleanly package subprojects/submodules of a mod in one "combined" JAR, while also allowing using them separately.

Nested JARs **are not**:

  * meant to be used on non-mod Java libraries,
  * always the best solution for libraries which can be safely shadowed under a different package. Keep in mind that a Fabric mod ID can only exist once, meaning that potential version conflicts could prevent a pack from loading - shadowed libraries do not have this problem.

In doubt, refer to this helpful chart:

{{:tutorial:nested_jar_chart.png?direct|}}

===== Incompatibilities =====

  * If your mod is using plugin-loader, please abandon it and adopt the entrypoints system instead.