Common Forge and NeoForge errors

Possible causes

• One mod crashed while Forge or NeoForge was setting it up.
• Missing or wrong-version dependencies.
• A mod for a different Minecraft version.
• A broken config file written by an earlier crash.

How to identify the cause

• The error screen and crash report list each failed mod with "Failure message". Read the first one; later failures are often side effects.
• Lines starting with Caused by explain the actual error.

Step-by-step fix

1. 1Note the first mod listed with a failure message.
2. 2Update it to the newest build for your Minecraft and loader version.
3. 3Install or update dependencies it reports.
4. 4If the error mentions a config file, delete that one file from config (back it up first) and let the mod recreate it.
5. 5Update Forge or NeoForge itself to the newest build for your Minecraft version, unless your modpack pins a specific build.

If that did not work

• Check the mod's issue tracker for the error message; many have known fixes or workarounds.

Affected versions

Forge and NeoForge, all versions.

Frequently asked questions