The UEFN edit session consistently crashes after approximately 10-15 minutes of navigating the level. The crash is preceded by a significant hitch (300ms+). The logs confirm this is a Fatal Error caused by exceeding the maximum number of UObjects allowed, with the object dump pointing to a potential leak or massive over-allocation of VerseNative.Concurrency_task_group (over 1 million instances).
Please select what you are reporting on:
Unreal Editor for Fortnite
What Type of Bug are you experiencing?
Stability
Steps to Reproduce
Launch the UEFN project (Having More than 10,000 entities [Can be empty entities having some component]).
Start an “Edit in Fortnite” (UEFN) session.
Once in the session, fly or run around the map, particularly moving around the entity locations.
Continue moving around the session for approximately 10 to 15 minutes.
The editor will experience a severe hitch, freeze, and then crash to the desktop.
Expected Result
The UEFN edit session should remain stable for an extended period, allowing for testing and editing without crashing.
Observed Result
The session crashes. The log files indicate the application ran out of its UObject allocation.
Additional Context (Project Details)
This is a large tycoon map with 8 bases.
The map heavily uses the Scene Graph Entity System. Each base has approximately 1,600 entities.
The map also contains ~2,400 instances (8 bases * 300 unique BPs) of blueprints that include skeletal meshes playing animations continuously, and some with Niagara VFX.
Analysis: The issue does not appear to be the memory limit (which we calculated at ~85,000 / 100,000). Instead, the crash is from the global UObject limit.
The log shows that VerseNative.Concurrency_task_group accounts for over 1 million UObjects, which is nearly 50% of the entire budget.
We’ve conducted a follow-up test to provide more data on this crash.
Test Performed:
We removed half of the content, reducing the world from 8 tycoon bases down to 4. All other systems, including the Scene Graph and Verse logic, remained the same for those 4 bases.
Observed Result:
The UEFN session still crashed with the exact same fatal error: Fatal error: ... Maximum number of UObjects (2162688) exceeded when trying to add 1 object(s)
Analysis:
This test strongly confirms our initial hypothesis. The problem is directly proportional to the amount of content (and its associated Verse logic) on the map.
By cutting the number of bases in half, we were able to observe that the UObject leak was still present. The new logs (attached) confirm this scaling: the number of VerseNative.Concurrency_task_group instances at crash time was reduced from ~1.06M (in the 8-base test) to ~701k, and Entity.Entity instances dropped from ~28.3k to ~24.1k.
This reinforces that the issue is not a one-time budget problem, but a leak that scales with the number of entities or scripts running. It simply took longer to hit the 2.16M UObject limit with half the content.
The primary suspect remains the massive allocation of VerseNative.Concurrency_task_group, which we believe is being spawned in a loop or is not being properly garbage-collected by our Scene Graph.
New Files Attached:
I have attached the new log files (FortniteGame.log.txt, CrashContext.runtime-xml, UEMinidump.dmp) from this 4-base test for your review.
We hope this helps narrow down the investigation. Thank you.
Thanks for sharing!
Crashes like this are tough, especially with so many entities. I’ve noticed similar issues in large bus simulator mod apk maps — too many objects or routes can cause lags if not optimized. Shows how crucial proper object management is in complex editors.
