creep.upgradeController(controller)
Spend carried Energy through WORK parts to add progress to an owned Controller.
Open in API reference →OBJECT HUB
Controller API Hub
A focused hub for Controller upgrading, downgrade risk, Safe Mode, reservation, claiming, tools, and return codes.
The current quick reference is anchored by creep.upgradeController() for Controller actions. Safe Mode, downgrade, reserve, and claim remain covered by the existing focused guides.
API
Covered API surfaces
These entries come from the shared quick-reference dataset. The highest-value surfaces stay visible; secondary entries remain available on demand.
RETURN CODES
High-signal return codes
These are the return-code paths already connected to this object in the site's existing guides and error reference.
ERR_NOT_OWNER return -1ERR_INVALID_TARGET return -7ERR_NOT_IN_RANGE return -9ERR_RCL_NOT_ENOUGH return -14Show more return codes · 1
GUIDES
Focused guides
Use the focused guides for workflow details instead of duplicating full tutorials on this hub.
PROVE
Runtime verification
Only guides that pass the existing Markdown acceptance boundary and have an accepted Console or live verification level appear here.
Screeps upgradeController(): Build Your First Upgrader Loop
Build one Upgrader1 loop that harvests from an active Source, moves within Controller range 3, spends Energy with upgradeController(), and switches state across ticks.
2026-08-11 · 2 evidenceOpen verified guide →