CRITICAL BUG REPORT: UEFN Crashes with EXCEPTION_INT_DIVIDE_BY_ZERO After Update 37.00

General Issues and Bug Reporting
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Summary

Bug Summary
Error Type: Unhandled Exception: EXCEPTION_INT_DIVIDE_BY_ZERO
Affected Version: UEFN after Fortnite Update 37.00 (August 7, 2025)
Severity: Critical - Complete inability to use UEFN
Platform: Windows 11
Problem Description
After the Fortnite 37.00 update released on August 7, 2025, UEFN has become completely unusable due to consistent crashes with the error “EXCEPTION_INT_DIVIDE_BY_ZERO”. This error occurs across multiple operations and makes it impossible to work with any projects.
When the Crashes Occur
The crash happens during these operations:

Opening existing projects - Any project that worked fine before update 37.00 now crashes immediately upon opening
Saving projects - Even newly created empty projects crash when attempting to save after making any changes (e.g., adding a default prop to the scene)
Synchronizing projects - Projects that require synchronization crash immediately when the sync button is pressed
Project creation - While new empty projects can be created and initially opened, any interaction that requires saving causes a crash

Steps Taken to Resolve
Complete System Reinstallation Attempted:

Full Windows reinstallation - Completely wiped and reinstalled Windows from scratch
Clean Epic Games Launcher installation
Fresh Fortnite and UEFN installation
Verified file integrity through Epic Games Launcher
Cleared all UEFN cache files in C:\Users[USERNAME]\AppData\Local\UnrealEditorFortnite\

Temporary Workaround Discovered:

Deleting contents of C:\Users[USERNAME]\AppData\Local\UnrealEditorFortnite\ allows creation and initial opening of new projects
However, any save operation immediately triggers the crash
This suggests the issue is with UEFN’s file writing/configuration management after the update

Error Details
Error Message: “An Unreal process has crashed: UE-FortniteGame”
Exception Type: EXCEPTION_INT_DIVIDE_BY_ZERO
Process: UE-FortniteGame

Impact Assessment

Complete work stoppage - Unable to continue development on existing projects
Data inaccessibility - Cannot access previously working projects
Development pipeline broken - Cannot save progress on new projects

System Specifications

OS: Windows 11
UEFN Version: Latest (post-37.00 update)
Epic Games Launcher: Latest version
Installation: Fresh install on clean system

Timeline

Before August 7, 2025: All projects working normally
August 7, 2025: Fortnite 37.00 update released
Immediately after update: All described issues began occurring
August 7, 2025: Attempted various troubleshooting including complete system reinstall - issues persist

Request for Resolution
This appears to be a critical bug introduced in update 37.00 that affects core UEFN functionality. Given that the issue persists even after complete system reinstallation, this suggests a fundamental problem with the update rather than user-specific configuration issues.
Urgently requesting:

Acknowledgment of this critical bug
Timeline for hotfix release
Temporary workaround recommendations
Option to rollback to previous stable UEFN version

Additional Notes

Multiple operations trigger the same EXCEPTION_INT_DIVIDE_BY_ZERO error
The crash occurs consistently and is reproducible 100% of the time
This is blocking all UEFN development work

Thank you for your urgent attention to this critical issue.

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Unreal Revision Control

Steps to Reproduce

Steps to Reproduce
Scenario 1: Opening Existing Projects

Launch Epic Games Launcher
Open UEFN (Unreal Editor for Fortnite)
Navigate to project browser
Click on any existing project that was working before update 37.00
Click “Open Project”

Scenario 2: Saving New Projects

Launch UEFN
Create a new blank project
Wait for project to load successfully
Add any default prop from Fortnite content browser to the scene
Press Ctrl+S or click File → Save

Scenario 3: Project Synchronization

Launch UEFN
Navigate to project browser
Select any project that shows “Needs Synchronization” status
Click “Synchronize” button

Expected Result

Expected Result

Scenario 1: Project should open normally and load into the UEFN editor interface
Scenario 2: Project should save successfully without any errors
Scenario 3: Project should synchronize with Epic Games servers and become available for editing

Observed Result

Observed Result

All Scenarios: Application crashes immediately with “Unhandled Exception: EXCEPTION_INT_DIVIDE_BY_ZERO” error dialog
Error Details:

Process: UE-FortniteGame crashes
No additional error information provided in crash dialog
Application terminates completely
No recovery possible without restarting UEFN

Consistency: 100% reproduction rate across all attempts
Workaround Limitation: Only clearing AppData\Local\UnrealEditorFortnite\ allows temporary access to new projects, but any save operation triggers the same crash

Platform(s)

Platform(s)

Operating System: Windows 11 (freshly installed)
UEFN Version: Latest version following Fortnite Update 37.00 (August 7, 2025)
Epic Games Launcher: Latest version
Hardware: Various configurations tested (issue persists across different hardware)
Installation Type: Fresh installation after complete system wipe
User Account: Administrator privileges confirmed

Thank you for your urgent attention to this critical issue.

Island Code

7068-6504-7419

2

Mine is doing the same thing

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3

Did you click on the 3 dots on the uefn part in the epic games launcher and click validate this helps certain things ?

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Hi @AtAshTag ,
Maybe its the same as the post. Has Epic built a new version and not given Windows Defender new template
urc.exe and urc.dll get flagged as Malware from Microsoft Defender - General / Issues and Bug Reporting - Epic Developer Community Forums

The crash is coming from Unreal Revision control Library code.
Try and make a new blank project and untick Revision control
Then see if the project generation now works.

We as indie developers dont have access to the URC library source so dont know what the name to put in Windows Defender for this urclib.dll ?

1 Like
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I couldn’t enter any project or create a new one right after the update, and I immediately checked the files twice before reinstalling everything together with Windows. It didn’t help after a clean installation, and yes, I checked the files after a clean reinstallation, it didn’t help either. The error is not on the client side, but on the server side, and it is related to version control revisions. Many people I know have written to me about version control problems and errors due to which they can’t enter their project after the update.

6

Same thing here

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FORT-950594 has been created and its status is ‘Unconfirmed’. This is now in a queue to be reproduced and confirmed.

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Thank you very much for your response!

Adding startup files to Windows protection exceptions and disabling protection completely did not bring success. But I found a way to isolate the editor crash error, but only for partial work.
I disabled revision version control when creating new projects, before creating a new project. Thus, we can now create a project that does not cause an error and can work in the editor without crashing.

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2894×611 78.1 KB

This is a big plus, we can create a new project and continue working. The downside is that if your old projects, like mine, used revision version control, then these projects cannot be opened, loaded, or synchronized.
I really hope that this problem will be solved and we will gain access to our projects.

Video - https://www.youtube.com/watch?v=E4BobIwR-v4

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I managed to get it started after a few crashes. I started with a new island template.

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hi @pythonchik_ua ,
That’s interesting switching off URC in your post above

The problem accessing your past URC entries is being investigated and a possible workaround was given by Epic Support in this post below

Error “Branch does not exist” in Unreal Revision Control - Development / Programming & Scripting - Epic Developer Community Forums

When the post says

Then for Windows 11 the means close UEFN and restart the PC before carrying out the above procedure.

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Thank you, but I had this problem on one project before the update, and I really solved the problem this way, but after the update, as we can see, I can no longer work with the version control revision in any project, now even if I put the project in a folder with projects in which there is no folder urc - the editor still gives an error and crashes.
On a newly created project without revisions of version control, when trying to enable it, it immediately crashes. But after rebooting, version control is enabled in the project, but if you move even the spawner along any axis - crashes.

Another scenario:

  1. Created a project without a version control system
  2. Added props
  3. Enabled the version control system
  4. Started a session
  5. Changed the location of the prop or saved - crash
  6. Entered the project after the crash.
  7. Disabled the version control system.
  8. Continue working calmly.
12

Did you find any fixes? I Still cannot open my projects that have Revision Control.

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I can’t open any of my old projects until this bug is fixed. You can only make a new one, but at the moment you won’t be able to open a project that had version control enabled. If someone finds a solution, let us know here.

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@pythonchik_ua @don2k74 @JeffreyBlanz @euLegacy could you all please zip up and share your logs folder that can be found at C:\Users\USERNAME\AppData\Local\UnrealEditorFortnite\Saved\Logs

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Logs.zip (1.3 MB)

Thank you for your attention to our question! This is the folder with my latest logs, but even today I have already deleted everything five times in the hope of somehow reviving old projects.

If you need logs with all types of crashes, write to me, I will conduct all the experiments so that all crashes are in the logs.

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UnrealEditorFortniteLog.zip (424.4 KB)

Here’s my latest logs.

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EpicGamesUpdaterService-2025.8.7-5.7.54-11326160817648198269.zip (648 Bytes)

18

Hello I got the same problem thank you for getting into it.
Logs.zip (14.2 MB)

19

same

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Thank you all for sharing your logs here, and for your patience as we’ve investigated this issue.

Thanks to your help we’ve found the root cause and have a fix in the works. Keep a lookout for an update to the editor that will include this fix as early as Wednesday.

5 Likes