Compatibility and Addons

🔌 Compatibility & Addons

Slimefun's addon ecosystem is one of its biggest strengths — and one of the main reasons Legacy has dedicated compatibility tooling.

Server software

Platform	Legacy status
Paper 26.2 / Minecraft 26.2	✅ Primary supported line
Purpur based on Paper 26.2	✅ Supported
Conventional Paper derivatives	⚠️ Often compatible, not guaranteed
Folia based on the target Paper line	⚠️ Experimental
Spigot / CraftBukkit / Bukkit	❌ Unsupported
Sponge	❌ Unsupported
Hybrid servers such as Arclight/Mohist/Cardboard	❌ Unsupported/blocked
Fabric / Forge / NeoForge	❌ Not a supported plugin runtime

The historical api-version: 1.16 in the plugin descriptor exists for compatibility behavior; it is not the supported Minecraft-version floor.

Addon compatibility statuses

Legacy can consume optional addon compatibility declarations. An addon without a declaration is not automatically blocked; it is reported as Undeclared.

A declaration can describe:

• tested Slimefun core variants;
• minimum Minecraft/Java versions;
• required platform capabilities;
• required and optional plugins;
• supported platform families;
• compatibility notes.

Missing required capabilities/plugins can produce an Incompatible diagnostic, while an untested core can produce a Warning.

CI-monitored addon families

The current compatibility matrix includes release-blocking Legacy forks and representative advisory probes.

Release-blocking Legacy probes

• FastMachines Legacy
• Networks Expansion Legacy
• SlimeTinker IE2 Legacy
• BetterChests Legacy

Representative/advisory probes

Examples currently include Networks upstream, Infinity Expansion 2, DynaTech, Supreme, Magic Expansion, FluffyMachines, FastMachines upstream, SlimeTinker upstream, FoxyMachines, FlowerPower, IDreamOfEasy, Gastronomicon, Bump, SlimeCustomizer and EMCTech.

Important

CI coverage is evidence, not a guarantee that your exact addon JAR is compatible. Versions, optional dependencies and local configuration still matter.

Check an installed server

Use:

/sf versions
/sf doctor compatibility
/sf doctor dependencies

Legacy may annotate addons with markers such as Deps!, Alias, Runtime!, Linkage! or Startup?. Read the hover/details before deciding the core is at fault.

External plugin dependencies

If an addon requires a library plugin, install the real dependency required by that addon. Legacy can diagnose declared dependencies and provider aliases; it does not emulate arbitrary third-party library classes.

Reporting an addon problem

Include:

• Paper/Minecraft version;
• Java version;
• Slimefun Legacy release/commit;
• exact addon JAR/version;
• full startup log and complete exception;
• reproduction steps;
• staging-server result;
• /sf versions output;
• relevant Doctor output.

This is far more useful than “addon X doesn't work.”