Debugging Machines and Recipes

MBD2 21.1.1

Use MBD gadgets to separate structure failures from recipe failures. Fix registration and machine wiring before debugging script callbacks.

Editor diagnostics, such as the controller-layer repetition rule shown here, should be resolved before testing the structure in-world.

Multiblock debugger

Use it on the intended controller. It can distinguish “not a controller,” a successfully formed structure, and predicate mismatch information. Work from the first mismatch: later positions may be wrong only because orientation or repetition was already misread.

Check controller facing, layer axis, controller placeholder, repetition range, exact versus partial states, and catalyst alternatives.

Recipe debugger

Use it on a machine with recipe logic. Compare raw matching with the modified recipe when recipe modifiers or KubeJS events are enabled. A failure normally belongs to one of four layers:

Layer	Typical cause
Recipe type	Wrong ID, recipe not loaded, XEI-hidden content mistaken for absent content
Condition	World/machine prerequisite currently fails
Routing	No matching trait, wrong recipe IO, slotName mismatch, distinct handler behavior
Storage	Filter, capacity, amount, rate, or output space prevents simulation

Debug probe blueprint

Bind built-in(mbd2:debug_probe) to the machine and right-click it holding the configured item (a stick by default): it reports machine state, tier and recipe status in chat, and consumes the click so the UI stays shut. Adding a block to one of its Info nodes extends the report. See built-in blueprints.

Useful development checks

• Log registry keys for machine definitions, recipe types, capabilities and conditions once after construction.
• Inspect machine.getAdditionalTraits() and each handler's capability, IO, slot names and distinct flag.
• Compare handler state before and after simulation; any change during simulation is a bug.
• Test one recipe content at a time, then add per-tick content, chance and conditions.
• Verify both server behaviour and client UI/XEI rendering.
• Check logs/latest.log after editing a blueprint — a graph that throws reports once, then goes silent.
• Remember that a runtime value override outlives the definition change that should have fixed it. Clear All Runtime Values, or break and replace the machine, when a setting refuses to take effect.