Fornite hard crashes on what seems to be corruption of a scene graph prefab with a verse component in it. Here is the log output of that which we are seeing happen A LOT..
[2026.06.17-18.00.41:904][362]LogWindows: Windows GetLastError: The operation completed successfully. (0)
[2026.06.17-18.00.42:385][409]LogProximityChat: [3cc6] Applying Mutator List Properties for Mutator [CreativeMutator_ProximityChat_C_2147482645].
[2026.06.17-18.00.42:385][409]LogFort: [9f03] Setting Proximity Chat [disabled] on the client for player [Vibin Gman]. Server changes will override this.
[2026.06.17-18.00.42:385][409]LogFort: [9f5d] Updating bLocalEnableCustomProximityChatPriorityList to [false]. IsProximityChatCustomPriorityListEnabled = [false].
[2026.06.17-18.00.42:385][409]LogFort: [9f56] Updating LocalProximityChatPriorityListProviderClass to [None]. IsProximityChatCustomPriorityListEnabled = [false].
[2026.06.17-18.00.42:385][409]LogFortHitches: HITCHHUNTER: Hitch in GameThread of 279.4 ms has been detected this frame. Number of Draw Calls this Frame: 101
[2026.06.17-18.00.42:385][409]LogThreadingWindows: Error: Runnable thread FAsyncLoadingThread crashed.
[2026.06.17-18.00.42:385][410]LogWindows: Error: === Critical error: ===
[2026.06.17-18.00.42:385][410]LogWindows: Error:
[2026.06.17-18.00.42:385][410]LogWindows: Error: Fatal error: [File:Unknown] [Line: 0]
[2026.06.17-18.00.42:385][410]LogWindows: Error: ObjectSerializationError: /a78b25ab-4414-9496-7977-2b9220070125/PlayerBasePrefab_V2 (0x8BFAF969B07144D0) /a78b25ab-4414-9496-7977-2b9220070125/PlayerBasePrefab_V2 (0x8BFAF969B07144D0) - PlayerBaseComponent /a78b25ab-4414-9496-7977-2b9220070125/PlayerBasePrefab_V2.Default__PlayerBasePrefab_V2_C:PlayerBaseComponent_0: Serial size mismatch: Expected read size 28, Actual read size 48
Please select what you are reporting on:
Unreal Editor for Fortnite
What Type of Bug are you experiencing?
Stability
Steps to Reproduce
Create a prefab and put a verse component in it that does something (no idea how to reproduce what could be in it). Work and check in and do normal things. Sooner or later this error will happen and it will crash Fortnite fully.
Expected Result
Fortnite never crashesā¦ prefab doesnāt corrupt? not sure, anything other than what is happening
Observed Result
fortnite crashes, prefab has to be completely deleted from the project and a new one created.
This has been happening in multiple of our projects a few times per day to random scene graph prefabs/components. Every time, we have to look at the logs to see which component/prefab is messed up, and then we can fix it by simply creating the same prefab/component from scratch, pasting in the code. The game will not run until we do this duplication. Additionally, these crashes persist in private codes, so public games would be crashing from this bug.
I had the same exact problem for hours last night. Had to quit because I was crashing more than I was working. Hereās a snippet from my log showing the size error on my entity / component.
Having this exact same issue and was crashing for an hour straight last night. I have always been able to stop crashing without deleting my entity. I believe the crashing stopped for me after clicking āFull recookā but that could be coincidental.
how do you click full recook if fortnite isnāt running though? Mine is greyed out after fortnite crashes and I canāt launch another session without crashing.
Hey all, thanks for the reports. Can we get full logs please? Appreciate the excerpts but please grab the full Fortnite client and UEFN editor logs so we have the full picture - How to get your Fortnite logs
Hereās what Iāve found based on the suggestion above. If I regularly āfull cookā the project then I havenāt had any crashes (crossing fingers hereā¦) but when I wasnāt doing that, it would have the serial mismatch and crash fortnite.
Doing a full cook is WAY better than crashing, having to restart after deleting the log file because at that point it was too big to open and look at, then crash again, then look at the log file and find the prefab that needs replacing. Then replace it, and then start a session again. It was a nightmare for productivity compared to just full recooking (if this is the actual solution at this pointā¦) I suspect full recooking was what was happening before 41.00 and the fancy button up top now to refresh sessions.
So.. if I were you guys, Iād take a look at what you did to the push mechanic for UEFN because it is not handling changes to prefabs after you make them and then push, it fully crashes fortnite and can be reliably made to happen. I donāt personally have any more time to keep trying to replicate bugs so Iām not taking chances with this as we have a tight timeline Iāve lost too much time on already to this bug, if it happens Iāll try to get a log file, but Iām really hoping it never happens again with the full recook strat. Hopefully you guys can sort that out, but maybe the above helps you get there.
The more people use scene graph the more this is bound to happen, and along with the instability of both URC and UEFN, I suspect itāll be a bigger problem than anybody would like sooner rather than later as scene graph is literally invaluable at this point.
I was pushing an update and in the back of my head knew I should have done a full recook and of course it crashes. Anyways, Iāve sent my logs to Flak directly so theyāre not out here in the public
I should note that after looking in the logs, this is a different crash entirely and has to do with persistence maybe? Not sure, itās the last thing in the log.
final note on the log files report I sent to Flak, this problem only affects me on my main computer. My alt on my laptop is fine and the other guy in the project has no crash on his computer. So itās either an account issue or a computer issue. I completely reinstalled UEFN and fortnite and it did not fix.
[2026.06.23-01.09.45:288][564]LogFortHitches: HITCHHUNTER: Hitch in GameThread of 298.3 ms has been detected this frame. Number of Draw Calls this Frame: 101
[2026.06.23-01.09.45:288][564]LogSocialChatManager: [3aa9] [00007FF0CE186CB0] ChannelName:NAW.Any.0cd4312bbaf34993978e2468d97de1a0.Minigame_PlayerCreated_C_2147482645 but we are waiting for a confirmation for:Channel:NAW.Any.0cd4312bbaf34993978e2468d97de1a0.Minigame_PlayerCreated_C_2147482645.3 - Set 0 seconds ago
[2026.06.23-01.09.45:288][564]LogSocialChatManager: [3af1] [00007FF0CE186CB0] ChannelName:NAW.Any.0cd4312bbaf34993978e2468d97de1a0.Minigame_PlayerCreated_C_2147482645 Conversation:[07LG4Ls2CLvWd8lecdQK0U02] with 0 players
[2026.06.23-01.09.45:288][564]LogSocialChatManager: [3ad5] [00007FF0CE186CB0] Joined ChannelName:NAW.Any.0cd4312bbaf34993978e2468d97de1a0.Minigame_PlayerCreated_C_2147482645 Conversation:07LG4Ls2CLvWd8lecdQK0U02 - still waiting for confirmation
[2026.06.23-01.09.45:288][564]LogFortGameUI: AFortInGameMapManager::RefreshCapture() success... trying to update content now.
[2026.06.23-01.09.45:288][564]LogThreadingWindows: Error: Runnable thread FAsyncLoadingThread crashed.
[2026.06.23-01.09.45:289][565]LogWindows: Error: === Critical error: ===
[2026.06.23-01.09.45:289][565]LogWindows: Error:
[2026.06.23-01.09.45:289][565]LogWindows: Error: Fatal error!
[2026.06.23-01.09.45:289][565]LogWindows: Error:
[2026.06.23-01.09.45:289][565]LogWindows: Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000000000000000
[2026.06.23-01.09.45:289][565]LogWindows: Error:
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ff62f4faf1d FortniteClient-Win64-Shipping.exe!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ff62f5e7efb FortniteClient-Win64-Shipping.exe!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ff62509022d FortniteClient-Win64-Shipping.exe!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ff62f473164 FortniteClient-Win64-Shipping.exe!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ff62f3e00f5 FortniteClient-Win64-Shipping.exe!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ff628b111e4 FortniteClient-Win64-Shipping.exe!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ff625e7389c FortniteClient-Win64-Shipping.exe!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error: [Callstack] 0x00007ffe0999257d KERNEL32.DLL!UnknownFunction []
[2026.06.23-01.09.45:289][565]LogWindows: Error:
[2026.06.23-01.09.45:289][565]LogWindows: Error: Crash in runnable thread FAsyncLoadingThread
I was able to reproduce the problem originally reported in this thread and Flak has the log files in discord when sheās back at her desk and free. The other problem is serious too and perhaps it needs a fresh bug report? I canāt resolve and canāt run a session on my main just yet.