This only happens in one of our projects, but anytime we attempt to Launch a Session or Push Changes after checking in something new related to Verse, UEFN crashes. This did not happen prior to v38.00. Returning to previous snapshots has the same issue, indicating this isn’t a change from our team.
Please select what you are reporting on:
Unreal Editor for Fortnite
What Type of Bug are you experiencing?
Verse
Steps to Reproduce
Make any change that requires Verse to compile.
Check-in said change into URC.
Select Launch a Session (or if a Live Edit Session is already live, select Push Changes)
UEFN will crash before the Live Edit Session (or Push Changes) can complete.
Crashing occurs regardless of whether we enable/disable URC (so unlikely to be a URC-related problem).
Crash is 85-95% of the time, but not 100% repro.
Description from our lead Verse developer:
We’ve been encountering consistent UEFN crashes since the 38.00 patch. The issue typically arises when syncing the latest changes, pushing updates, or compiling Verse code—even when no code modifications have been made. The crash occurs regardless of whether Fortnite is running. Interestingly, the first time UEFN is launched and a PIE session is initiated, everything loads correctly and the crash does not occur. However, after ending that initial game, subsequent attempts to compile verse or push changes—regardless of whether anything has changed—almost always result in a crash.
To investigate, I attempted a binary search through our snapshots to identify a potential trigger. While the results were inconsistent, I noticed that snapshots prior to approximately #1200 (we currently have around 1800) do not cause crashes, even after multiple Verse compiles. Beyond that point, UEFN tends to crash after two or three compiles. That said, the behavior isn’t entirely predictable—sometimes snapshot close to #1200 compiles successfully ten times in a row, but then crashes unexpectedly after a 30 min delay.
I’ve also attempted several troubleshooting steps based on recommendations I found online, including verifying UEFN files, uninstalling and reinstalling both Fortnite and UEFN, and adding the UEFN and URC executables to the Windows Defender exclusion list. Unfortunately, none of these measures resolved the issue.
