Upgrade Planner fails with Loader Utils due to missing item prototypes

Description and use

The Upgrade Planner fails because Loader Utils creates hidden clones without item prototypes. The fix is to disable 'Loaders are lane filtered by default' in mod settings.

Problem

The Upgrade Planner cannot upgrade loaders when using Loader Utils because the mod creates hidden script-only entity clones (lf/rl/fs variants) without backing item prototypes, which the vanilla upgrade planner requires to build entities.

Outcome

The issue stems from Loader Utils replacing loaders with hidden clones that lack item prototypes. Disabling the default lane filtering setting restores the item-backed prototypes, enabling the Upgrade Planner to work.

Workflow

• Install Loader Utils, Deadlock's Beltboxes and Loaders, and Deadlock's Stackboxes.
• Attempt to upgrade loaders using the vanilla Upgrade Planner.
• Identify that upgrades fail on loaders but succeed on Beltboxes.
• Verify that upgrades work when lane filtering is disabled.
• Investigate the source code to understand the interaction.
• Disable 'Loaders are lane filtered by default' in mod settings.
• Re-test upgrades, which now succeed.

Evidence

Loader Utilities doesn't just watch loaders — it silently replaces them. Every time a loader is built... it calls a replace() function that mines the entity you just placed and spawns a *different* hidden prototype in its place...

Source

The lf-rl-fs variant loader prototypes created in data-final-fixes.lua have no backing item, so the Upgrade Planner can't build them — not even via the next_upgrade chain you set up correctly for them.

Source

Go to Settings → Mod Settings → Per Player and turn off 'Loaders are lane filtered by default.' With all three defaults off, freshly-placed loaders stay as Deadlock's real, item-backed prototypes, and the upgrade planner should work exactly as it does with loader-utils disabled.

Source