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Sledgehammer utilises SpongePowered/Mixin to patch issues in Minecraft and Forge mods.


Client Patches

Common Patches

  • Prevent crashes due to invalid translation keys
  • Make LazyLoad Thread-safe (Should fix MC-68381)

Server Patches

  • Print a single message instead of a stacktrace for advancement errors
  • Don't reload Advancements on World Load (Fixes Achievement issues on SkyFactory 4)
  • Fix NullPointerException in BiomeProvider::findBiomePosition
  • Prevent Grass turning into Dirt
  • Prevent Ice turning into Water
  • Prevent Totemic from changing the weather
  • Chunk Saving

    • Alert players when a chunk fails to save
    • Remove all Entities and TileEntities from chunks that fail to save
    • Remove all blacklisted items from chunks that fail to save
    • Generate a crash report and safely stops the server if a chunk fails to save
  • Reduce Network usage by postponing flush
  • Fix
  • Redirect inventory debugging messages added by Sponge
  • Fix MC-134716 - Player kick exploit
  • Prevent or delete any items that attempt to teleport across dimensions
  • Limit books to 50 pages with 255 characters for each
  • Fix potential deadlock on shutdown
  • Prevent ConcurrentModificationException in PlayerChunkMap
  • Fix Item spawn packet exploit with ProjectRed
  • Fix
  • Redirect Ruins debugging messages
  • Fix (Sponge only)
  • Force permission check for OP based commands (Sponge only)
  • Fix Misty World portal issues (Sponge only)
  • Fix (Fixed in 0.6.56 according to Dev) (Sponge only)
  • Prevent movement outside of the world border (Sponge only)
  • Prevent sending blank death messages (Sponge only)


The jar containing '-sponge' does not contain these dependencies as they are already present in a Sponge environment.



GitHub (1.12.2)


Sledgehammer is licensed under the Apache 2.0 license.

You are allowed to include this mod in your modpack.