warning

KubeJS recipes failed to load

Q: What does "Failed to parse recipe 'kubejs:custom_recipe'! Falling back to vanilla: Unknown item 'minecraft:not_a_real_item'" mean?

KubeJS recipes failed to load. KubeJS could not build these recipes, so in game they are missing or fell back to vanilla. The pack's scripts reference ingredients that do not exist or are empty. Look in kubejs/server_scripts for the recipe id and fix the ingredient it names. If this is a stock modpack, update it and report the recipe to the pack author; nothing on the server side changes this.

Q: How do I fix "Failed to parse recipe 'kubejs:custom_recipe'! Falling back to vanilla: Unknown item 'minecraft:not_a_real_item'"?

1. Find the script: The recipe id in the line, such as kubejs:custom_recipe, is defined in kubejs/server_scripts. Search that folder for the id. 2. Fix the ingredient: The error names the unknown item or tag. Check the mod that provides it for the current id; mod updates rename items more often than people expect. 3. Reload without a restart: /kubejs reload server_scripts or /reload re-runs the scripts. The line disappears when the recipe builds. 4. On a stock pack, update it: Check the pack for a newer version, and if the error persists there, report it to the pack author with the line. Nothing server-side fixes a pack script.

Applies to Forge, NeoForge, Fabric, Quilt.

What it looks like in your log

Failed to parse recipe 'kubejs:custom_recipe'! Falling back to vanilla: Unknown item 'minecraft:not_a_real_item'

What causes it

KubeJS could not build these recipes, so in game they are missing or fell back to vanilla. The pack's scripts reference ingredients that do not exist or are empty.

How to fix it

Look in kubejs/server_scripts for the recipe id and fix the ingredient it names. If this is a stock modpack, update it and report the recipe to the pack author; nothing on the server side changes this.

Why it happens

KubeJS lets a modpack define recipes in scripts. When a script references an item or tag that does not exist, KubeJS cannot build that recipe and logs one line per failure at start-up. The server keeps running; the recipe is just missing in game, or has fallen back to the vanilla one. Players notice when a crafting table refuses a recipe the pack wiki says exists.

On a stock modpack these lines are the pack author's problem, usually from a mod update that renamed an item. On a custom pack they are yours.

Fix it step by step

1Find the scriptThe recipe id in the line, such as kubejs:custom_recipe, is defined in kubejs/server_scripts. Search that folder for the id.
2Fix the ingredientThe error names the unknown item or tag. Check the mod that provides it for the current id; mod updates rename items more often than people expect.
3Reload without a restart/kubejs reload server_scripts or /reload re-runs the scripts. The line disappears when the recipe builds.
4On a stock pack, update itCheck the pack for a newer version, and if the error persists there, report it to the pack author with the line. Nothing server-side fixes a pack script.

If that didn't work

If every recipe in a script fails, the script itself has a syntax error and KubeJS logged that first, further up. Fix the syntax and the individual lines go away.

Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.

Check your own log