[UEFN] MODULE VALIDATION FAILED – download_failure 404 – Module stuck

[HASHCHUCHU]

Summary

UEFN session validation failing with download_failure 404 after power outage – module stuck in backend

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Other

Steps to Reproduce

1. Open UEFN
2. Open any project (including new blank projects)
3. Click “Start Session”
4. Wait for validation
5. Session fails with MODULE VALIDATION FAILED and download_failure 404

Expected Result

UEFN should validate project modules successfully and launch the live session without backend validation errors.

Observed Result

The session fails during validation with:

FlowStep_ResolveSessionCandidates()
errors.com.epicgames.pre-processing.download_failure
Response code 404

The project cannot start a live session.

Platform(s)

pc

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Additional Notes

This issue started immediately after a power outage while I was in a live UEFN session.

Since then:

• The error persists for several days
• It affects all projects on my account
• Another Epic account works normally on the same PC

This strongly indicates a backend module corruption or a stuck Valkyrie validation state linked to my account.

[Jimbohalo10]

hi @HASHCHUCHU

Due to power fail you need to verify UEFN/Fn install

how to verify UEFN

The next thing is to Launch menu → Validate all project fix any errors

[HASHCHUCHU]

Hi,

Thank you for the suggestion.

I already reinstalled both Fortnite and UEFN completely (including formatting Windows), and the issue persists.

Another Epic account works normally on the same PC, which suggests this is not an installation issue.

Additionally, new blank projects also fail with the same error.

This appears to be account-related backend validation (module download_failure 404).

Could this be escalated to someone who can check the module state on the backend?

Thank you.

[0xrhsmt (ryosevenf)]

I’m experiencing the same issue.

[Flak]

@HASHCHUCHU could you send us fresh logs after you reproduce this? Thank you!

[Flak]

How to get your Fortnite logs

At times, we will ask you to send us your logs when you’re having an issue in UEFN. Here is how to do that: UEFN Logs Exit Fortnite. Click on Start or press the Windows Key + R. Type \AppData\Local\UnrealEditorFortnite\Saved\Logs and press Enter. Zip your Logs folder and attach the zip file to your reply. To find UEFN Logs while working in UEFN: Click “Output Log” at the bottom of the window. Click on “Setting” at the top right of the window Click “Open Source Location” Zip your Logs folder…

[HASHCHUCHU]

Logs.rar (19,1,MB)

[Flak]

Thank you!

[Flak]

Hi @HASHCHUCHU We’ve put in a few fixes for things that seem like this same error. Is this still happening to you?

[Bug-Reporter]

FORT-1067903’s status has changed to ‘Ready for QA’. A member of the QA department is investigating the issue.

[HASHCHUCHU]

Good evening, I cleared the cache using UEFN itself, as another developer instructed in another post, and I was able to log back into my account. Thank you very much.