patch · June 17, 2025

Stellaris Update 4.0.21 Balances Necrophages and Fixes Megastructure Storms

Stellaris patch 4.0.21 stops Storm Aftermath events from disrupting almost-finished megastructures and buffs Necrophage growth mechanics. The update also addresses multiplayer save speeds and colony-breaking bugs.

Stellaris patch 4.0.21 is available now, bringing bug fixes, quality-of-life adjustments, and mechanical balance changes to the galaxy.

Megastructures and Storm Adjustments

Storm Aftermath events no longer trigger in systems where players are constructing megastructures. This prevents random anomalies from spawning under nearly complete Dyson swarms. Additionally, multiplayer save game transfer speeds are increased by default, though hosts can revert to the previous transfer mode through settings if connection issues arise.

Necrophage and Empire Balance

Necrophages receive several adjustments. Pops with the Necrophage trait can now grow slowly even while other pops are being necrophaged on their planet, and the pop growth speed penalty drops from -75% to -50%. Necrophage empires now start with more of their prepatent species and fewer Necrophage species, alongside fixes to prevent starting unemployment. The Resettlement Prohibited policy now grants +100% automatic migration, and Machine Worlds now always maintain their maximum job capacity.

Colony and Event Bug Fixes

The Purity Breach and Fatal Mutations events can no longer destroy colonies. Memorialists now correctly grant their priests the ethics modifiers shown on civic tooltips, and reforming government into Genesis Guides permits building Genesis Arks. Ringworld districts now spawn correctly on pre-ftl ringworlds, and gestalt empires can access fallen empire trade buildings.

Why this patch matters

Patch 4.0.21 removes environmental interruptions near megastructures while making Necrophage empires more stable.