Tinkers Construct not working? Crash and loading fixes

Work through the usual causes of crashes and missing content, and learn where the game writes its logs.

Published October 20, 2026 3 min read Fixes
Illustration of gears, a wrench and a warning sign for troubleshooting

Most Tinkers Construct problems come from a small set of causes: a missing library, mismatched versions, or a conflict with another mod. Work through this list in order.

Do these first

The SlimeKnights FAQ recommends the same starting steps for nearly every issue:

  1. Update Tinkers' Construct and Mantle to the latest versions for your Minecraft version.
  2. Test with only Tinkers and Mantle installed to see whether another mod is involved.
  3. Search the issue tracker on GitHub before reporting.

Crash on startup

  • Mantle is missing. Tinkers needs Mantle. Add the matching jar to the same mods folder.
  • Wrong Minecraft version. A 1.20.1 jar will not load on 1.20.4 or 1.21.1.
  • Wrong loader. Forge/NeoForge jars do not load on Fabric or Quilt.
  • Duplicate jars. Two versions of Tinkers or Mantle in one folder cause errors — keep one of each.

Mod not in the mods list

  • Check that you launched the Forge or NeoForge profile, not vanilla.
  • Confirm the jar is in the mods folder of the instance you are launching.
  • Make sure the file still ends in .jar and was not unzipped.

Can't join a server

Client and server need the same loader version, the same Tinkers version and the same Mantle version. The disconnect screen usually names the mod that differs.

Missing recipes or config

Install JEI to see the recipes actually loaded in your game. Modpacks often change Tinkers recipes. The SlimeKnights FAQ also notes that some options that used to be in config files are now controlled by data packs.

Smeltery problems

If the smeltery won't form, check every floor and wall block, and make sure the controller, tank and drain are part of the wall. If nothing melts, check the fuel tank. Our smeltery guide covers this in detail.

Reading logs

When the game crashes, it writes a report to the crash-reports folder in your game directory, and a full log to logs/latest.log. Look near the top of the crash report for a line naming a mod, and search the log for "Mantle" or "tconstruct".

Reporting a bug

If the issue happens with only Tinkers and Mantle installed, and you can't find it in the tracker, report it on the Tinkers' Construct GitHub with your versions, steps to reproduce and the crash report. For general help, the SlimeKnights community Discord is listed on the project page.

Need to reinstall cleanly? Follow the install guide.