# \[UEFN\] MODULE VALIDATION FAILED – download\_failure 404 – Module stuck **URL:** \ **Category:** Issues and Bug Reporting\ **Tags:** closed, unreal-editor-for-fortnite\ **Created:** [February 28, 2026, 6:13am UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832 "2026-02-28T06:13:05Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![HASHCHUCHU](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@HASHCHUCHU](https://forums.unrealengine.com/u/HASHCHUCHU)\ **Post date:** [February 28, 2026, 6:13am UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/1 "2026-02-28T06:13:05Z")
### 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 ### Upload an image ![Screenshot 2026-02-26 152049.png](https://d3kjluh73b9h9o.cloudfront.net/original/4X/5/f/4/5f401b7b48d259a89ddb5e5d252f80acd9a286d7.png) ![Screenshot 2026-02-28 053349.png](https://d3kjluh73b9h9o.cloudfront.net/original/4X/4/6/9/469f37adfd4283235a6b4f37d5b1b07db2009ca4.png) ### 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. ---
**Author:** ![Jimbohalo10](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/jimbohalo10/32/961440_2.png) [@Jimbohalo10](https://forums.unrealengine.com/u/Jimbohalo10)\ **Post date:** [February 28, 2026, 11:33pm UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/2 "2026-02-28T23:33:32Z")
hi @HASHCHUCHU Due to power fail you need to verify UEFN/Fn install [how to verify UEFN](https://forums.unrealengine.com/t/urc-exe-and-urc-dll-get-flagged-as-malware-from-microsoft-defender/1802519/5) The next thing is to Launch menu → Validate all project fix any errors ---
**Author:** ![HASHCHUCHU](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@HASHCHUCHU](https://forums.unrealengine.com/u/HASHCHUCHU)\ **Post date:** [March 1, 2026, 9:51am UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/3 "2026-03-01T09:51:10Z")
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. ---
**Author:** ![0xrhsmt](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@0xrhsmt](https://forums.unrealengine.com/u/0xrhsmt)\ **Post date:** [March 6, 2026, 3:36am UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/4 "2026-03-06T03:36:09Z")
I’m experiencing the same issue. ---
**Author:** ![Flak](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/flak/32/769441_2.png) [@Flak](https://forums.unrealengine.com/u/Flak)\ **Post date:** [March 9, 2026, 5:58pm UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/6 "2026-03-09T17:58:42Z")
@HASHCHUCHU could you send us fresh logs after you reproduce this? Thank you! ---
**Author:** ![Flak](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/flak/32/769441_2.png) [@Flak](https://forums.unrealengine.com/u/Flak)\ **Post date:** [March 9, 2026, 5:59pm UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/7 "2026-03-09T17:59:17Z")
> [@How to get your Fortnite logs](https://forums.unrealengine.com/t/how-to-get-your-fortnite-logs/682382): > > 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… ---
**Author:** ![HASHCHUCHU](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@HASHCHUCHU](https://forums.unrealengine.com/u/HASHCHUCHU)\ **Post date:** [March 17, 2026, 8:49pm UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/8 "2026-03-17T20:49:18Z")
[Logs.rar](https://forums.unrealengine.com/uploads/short-url/A12A37sJ84krh3tfztpZT0eoiHs.rar) (19,1,MB) ---
**Author:** ![Flak](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/flak/32/769441_2.png) [@Flak](https://forums.unrealengine.com/u/Flak)\ **Post date:** [March 18, 2026, 2:12pm UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/9 "2026-03-18T14:12:56Z")
Thank you! ---
**Author:** ![Flak](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/flak/32/769441_2.png) [@Flak](https://forums.unrealengine.com/u/Flak)\ **Post date:** [April 8, 2026, 2:01pm UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/11 "2026-04-08T14:01:43Z")
Hi @HASHCHUCHU 🙂 We’ve put in a few fixes for things that seem like this same error. Is this still happening to you? ---
**Author:** ![HASHCHUCHU](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@HASHCHUCHU](https://forums.unrealengine.com/u/HASHCHUCHU)\ **Post date:** [April 14, 2026, 3:19am UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/13 "2026-04-14T03:19:54Z")
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. ---
**Author:** ![Bug-Reporter](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/bug-reporter/32/997076_2.png) [@Bug-Reporter](https://forums.unrealengine.com/u/Bug-Reporter)\ **Post date:** [June 17, 2026, 7:00pm UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/14 "2026-06-17T19:00:30Z")
FORT-1067903 has been ‘Closed’. We’re unable to reproduce this issue. ---
**Author:** ![system](https://d3kjluh73b9h9o.cloudfront.net/original/4X/7/1/3/713c9d3f58553f0de89543d76a8a3a2779dc9fa4.png) [@system](https://forums.unrealengine.com/u/system)\ **Post date:** [August 27, 2026, 6:13am UTC](https://forums.unrealengine.com/t/uefn-module-validation-failed-download-failure-404-module-stuck/2702832/15 "2026-08-27T06:13:28Z")
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