Factorio 2.1.20 Fixes Stalled Platform Inserters and Rocket Signals
The experimental patch addresses hub sorting, missed rocket-launch signals and mod API changes. Check your branch before updating.
Stalled space-platform inserters and missed rocket-launch signals are among the fixes in Factorio 2.1.20. Wube's September 22 release notes describe an experimental update, so check your branch before expecting the changes in an existing installation.
Platform hubs and rocket silos
Sorting a platform hub's inventory could fail to wake inserters, leaving a setup stuck in a way that looked like a deadlock. The patch fixes that wakeup problem. If your platform stopped moving items after sorting, retest it on the updated build before redesigning the layout.
Rocket silos had a separate timing issue: launches could happen too quickly for the circuit network to register them. Wube also restores walking between horizontally adjacent silos and fixes science-production figures missing from the statistics for their corresponding surfaces.
The notes include a performance fix for artillery reaction groups, without benchmark figures. Several specific crashes and a mod-related platform freeze are addressed too; this is not a claim that every crash or stalled factory is fixed.
Check the experimental branch and your mods
On Steam, select experimental under Beta Participation in the game's settings. Standalone players can enable Experimental updates under Other settings. The announcement does not promote 2.1.20 to the stable branch.
Mod compatibility deserves a check before loading a long-running factory. The item prototype's fuel_category field becomes fuel_categories, and the equivalent Lua item read API changes too. The base-game binary also stops trying to install mods that require Space Age.
Keep a backup before switching a modded save to a new build, and check whether its mods support 2.1.20. For an affected experimental installation, update and retry the documented logistics failure before spending time rebuilding around it.