Troubleshooting

Startup crash: mm:mm:<id> or ResourceLocationException

If startup fails with an error like:

ResourceLocationException: Non [a-z0-9/._-] character in path of location: mm:mm:big_sieve_basic

check your KubeJS startup registrations. These events expect a bare MM id/path in event.create(...):

MMEvents.registerControllers(event => event.create('coke_oven'))
MMEvents.registerExtraBlocks(event => event.create('basic_circuit'))
MMEvents.registerPorts(event => event.create('item_port'))

Do not pass mm:coke_oven, mm:basic_circuit, or mm:item_port to those startup registration events. The mod registers generated blocks/items under the mm namespace internally. Structures and process recipes are different: use full resource ids there, such as expert:coke_oven or expert:coke_oven/charcoal.

The controller block exists but the structure will not form

Check these first:

1. The structure file is under data/<namespace>/mm/structures/.
2. controllerIds contains the controller id, not the block registry name unless those happen to match.
3. Every character used in layout has a corresponding entry in key.
4. Air is represented by a space character in layout strings, not by a key entry.
5. Port pieces use the correct input/output side. input: true requires an input port; input: false requires an output port.
6. If using portType, confirm the port config tierRank satisfies minTier and maxTier.
7. If using blockstate properties, confirm the placed block has exactly those property values.

Recipes show in JEI but do not run

Check:

1. structureId exactly matches the structure id.
2. The structure is currently formed.
3. Inputs are available in input ports.
4. Outputs have room in output ports.
5. Conditions pass, for example dimension/weather.
6. Energy/fluid/chemical units are large enough for the recipe.
7. If per_tick = true, the port must satisfy the amount every tick, not just once.

Item NBT recipe does not match

Use nbt as a JSON object or nbt_snbt as a string. Start with weak/default matching, then switch to nbt_match: "strong" only when you need an exact match.

Auto-output does nothing

Only compatible ports support autoPush. Set it on the port config:

"config": {
  "rows": 3,
  "columns": 3,
  "autoPush": true
}

If omitted, the value comes from portsAutoExtractByDefault in mm-common.toml.

Too much server cost

Use these config levers:

structureValidationRate = 10
maxParallelRecipes = 5

Increasing structureValidationRate makes controllers re-check less often. asyncValidation is present in the config file, but verify its behavior against the exact build you are shipping. Reducing parallelism and large recipe throughput can also help.

After editing structures, old controllers behave weirdly

Try:

/mm reform

This refreshes/reforms controller state for controllers in loaded chunks around players.