update · June 19, 2025
Stellaris Update 4.0.21 Adjusts Necrophages, Slows Patch Cadence
Stellaris patch 4.0.21 buffs Necrophage growth, fixes event bugs, and improves multiplayer save transfers. Developer Paradox also announced a slower patch cadence moving forward to allow for more thorough internal testing.
Paradox Interactive released update 4.0.21 for Stellaris, bringing balance adjustments to Necrophages and machine empires alongside a long list of bug fixes. Along with the patch, the development team announced a shift in its release strategy, slowing down live updates in favor of a more deliberate testing cycle.
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. The pop growth speed penalty for the trait drops from minus 75 percent to minus 50 percent, and empires begin with more of their prepatent species and fewer Necrophage species. Additionally, starting with multiple species should no longer cause unemployment. Machine Worlds now always have their maximum number of jobs, and Resource Consolidation starts with fewer generator and mining districts because those districts provide 600 jobs each. Resource Consolidation also drops the Malfunctioning Replicator Bay blocker. Banning manual resettlement through the Resettlement Prohibited policy now grants plus 100 percent automatic migration.
Bug Fixes and Event Adjustments
Storm Aftermath events no longer trigger in systems where you are constructing megastructures. Memorialists now correctly grant their priests ethics modifiers, and Genesis Guides allow building Genesis Arks. The Purity Breach and Fatal Mutations events can no longer destroy colonies. Evolutionary Predator empires can once more gain and keep the Psionic Ephase trait, and Entrepreneur traits once again grant Commercial Pact Efficiency. Serviles no longer end up as specialists or elites, and AI empires now respond dynamically to Status Quo peace deals instead of using generic text.
Multiplayer and Interface Improvements
Save game transfer speed is increased in multiplayer by default, with hosts able to revert to the former transfer mode through settings if issues occur. The colonize planet button is now accessible on the management tab as well as the surface tab. Modders gain a new refresh_auto_generated_ship_designs effect.
Future Update Strategy
Paradox is altering its release schedule to address stability issues caused by rapid patching. Live patches will occur less frequently, with the next update expected around August. The team is shifting focus to Open Betas, starting with the Wilderness Open Beta, to allow internal QA more time to vet changes before pushing them to the live game.
Why this patch matters
Update 4.0.21 resolves several frustrating bugs and rebalances Necrophages, but the bigger news is Paradox pressing the brakes on its rapid update schedule to prioritize stability.