# Unable To Play: Failed to upload source files 

**URL:** <https://forums.unrealengine.com/t/unable-to-play-failed-to-upload-source-files/2728802>\
**Category:** Issues and Bug Reporting\
**Tags:** unreal-engine, unreal-editor-for-fortnite, bug-report, editor\
**Created:** [June 15, 2026, 2:27pm UTC](https://forums.unrealengine.com/t/unable-to-play-failed-to-upload-source-files/2728802 "2026-06-15T14:27:22Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Funsockman](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Funsockman](https://forums.unrealengine.com/u/Funsockman)\
**Post date:** [June 15, 2026, 2:27pm UTC](https://forums.unrealengine.com/t/unable-to-play-failed-to-upload-source-files/2728802/1 "2026-06-15T14:27:22Z")

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### Summary

For some reason, as I upload my verse code, it decides to stop letting me upload it.

LogValkyrie: Error: FlowStep\_UploadCandidateSourceFiles(): Failed to register session candidates: [Failed to upload sources for module : Error=[Failed to connect to remote lores://urc-uefn.live.ucs.on.epicgames.com: authorize: Failed sending command: Server returned error code 2 | Internal(Internal { source: StringError(“authorize: Failed sending command: Server returned error code 2”), trace: Trace { locations: , overflow: false } })]]  
LogValkyrie: Error: FlowStep\_UploadCandidateSourceFiles(): Failed to register session candidates: [Failed to upload sources for module : Error=[Failed to connect to remote lores://urc-uefn.live.ucs.on.epicgames.com]]

### Please select what you are reporting on:

Unreal Editor for Fortnite

### What Type of Bug are you experiencing?

Assets

### Steps to Reproduce

Trying to upload changes with f5 or f6, or pressing the start button. Also, I tried duplicating the project, which actually worked. So, I could just make another copy and continue, but it is getting annoying.

### Expected Result

It would probably work on your end.

### Observed Result

It says failed to upload.

### Platform(s)

Dell 14 Pro (Laptop)

### Island Code

8864-7947-5648

### Upload an image

 ![FailedToUpload.png](https://d3kjluh73b9h9o.cloudfront.net/original/4X/d/e/e/dee0bdee496ac513c49f1df13d4ea6eb47f8e079.png)

### Additional Notes

I am using the physics feature.

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**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:** [June 15, 2026, 6:40pm UTC](https://forums.unrealengine.com/t/unable-to-play-failed-to-upload-source-files/2728802/2 "2026-06-15T18:40:14Z")

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hi @Funsockman

There is a know problem which can be found in the log file that is stopping for lori uploading

[v41.00 Known Issues & Pre-Release Updates - General / Issues and Bug Reporting - Epic Developer Community Forums](https://forums.unrealengine.com/t/v41-00-known-issues-pre-release-updates/2726053/4)

- If you do, please clear the following directory and try again.

`%LOCALAPPDATA%/UnrealEditorFortnite/Intermediate/ValkyrieUploadTemp`

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**Author:** ![Funsockman](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Funsockman](https://forums.unrealengine.com/u/Funsockman)\
**Post date:** [June 15, 2026, 11:39pm UTC](https://forums.unrealengine.com/t/unable-to-play-failed-to-upload-source-files/2728802/3 "2026-06-15T23:39:39Z")

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Hi JimboHalo10! Thank you very much for your help! That is great! I appreciate it so very much. I hope you have a wonderful day.

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**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:** [June 16, 2026, 8:10pm UTC](https://forums.unrealengine.com/t/unable-to-play-failed-to-upload-source-files/2728802/4 "2026-06-16T20:10:22Z")

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Yes, thank you, @Jimbohalo10. Closing this one so a ticket doesn’t get created.

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**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:** [June 16, 2026, 8:10pm UTC](https://forums.unrealengine.com/t/unable-to-play-failed-to-upload-source-files/2728802/5 "2026-06-16T20:10:26Z")

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