Summary
Starting immediately after the Fortnite 39.00 update (Nov 29–30 2025), all of my AI-heavy islands that use custom npc_behavior scripts combined with NPC Spawner / Guard Spawner devices began experiencing extreme server instability. These islands were 100% stable for over a month prior to 39.00 with no Verse changes on my side.
Since 39.00, these islands now produce 20–100 server crashes per day, affecting live players in public matches. This regression impacts multiple islands, multiple spawners, and multiple behavior implementations, all of which previously ran flawlessly.
This appears to be a core AI / Scene Graph / NPC component regression introduced in 39.00.
When the Issue Started
Approximately 24–36 hours after v39.00 went live, every island using custom NPC logic started producing:
Server crashes
NPC freezes / desyncs
Hard AI shutdown during runtime
Public matches collapsing with identical error types
No code was changed during this window. Maps that had been stable for 30+ days immediately started failing.
Number of Maps Affected
Hunt the Spino
Hunt the Santa
Hunt the T-Rex
Additional prototype islands using the same AI framework
All show identical problems starting after 39.00.
Frequency
100–1500 server crashes per day per map, verified across:
Public matches
Long private sessions
Dedicated test runs
Please select what you are reporting on:
Unreal Editor for Fortnite
What Type of Bug are you experiencing?
AI
Steps to Reproduce
Have Custom NPC code in your project
Expected Result
Servers not crash
Observed Result
NPCs work but servers crash now
Platform(s)
All