# Cannot launch session; given errors that I cannot fix. **URL:** \ **Category:** Issues and Bug Reporting\ **Tags:** unreal-engine, fortnite-creative, unreal-editor-for-fortnite, editor\ **Created:** [May 10, 2025, 3:01am UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976 "2025-05-10T03:01:08Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![DRAW12](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/draw12/32/1062897_2.png) [@DRAW12](https://forums.unrealengine.com/u/DRAW12)\ **Post date:** [May 10, 2025, 3:01am UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/1 "2025-05-10T03:01:09Z")
### Summary After the 35.00 update, I cannot launch session or upload a private version of my project. I am given barebones errors from uefn simply stating that my project failed to upload. It has done this for the past week. ### Please select what you are reporting on: Unreal Editor for Fortnite ### What Type of Bug are you experiencing? Other ### Steps to Reproduce After the 35.00 update, I am given errors that prevent me from launching session/ launching private versions. ### Expected Result The session Should be able to launch, and private codes should be able to be created. ### Observed Result Instead, errors appear and the session/private code is unable to be created. ### Platform(s) PC ### Island Code 6100-3067-4349 ### Upload an image ![Screenshot 2025-05-09 224352.png](https://d3kjluh73b9h9o.cloudfront.net/original/4X/5/6/1/561ac4e3deb8b03a91868305f48b43b637f961d7.png) ### Additional Notes This issue has been happening to me for the past week now, and I have been physically unable to playtest my project because of these errors. ---
**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:** [May 10, 2025, 5:29am UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/2 "2025-05-10T05:29:07Z")
hi @DRAW12 , Looks like your installation is corrupted Delete directory ```auto C:\Users\USERNAME\AppData\Local\UnrealEditorFortnite\Intermediate\ValkyrieUploadTemp ``` Verify installation with [How to Verify Fortnite/UEFN](https://forums.unrealengine.com/t/urc-exe-and-urc-dll-get-flagged-as-malware-from-microsoft-defender/1802519/5) ---
**Author:** ![DRAW12](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/draw12/32/1062897_2.png) [@DRAW12](https://forums.unrealengine.com/u/DRAW12)\ **Post date:** [May 10, 2025, 7:56pm UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/3 "2025-05-10T19:56:53Z")
I verified files and opened the editor to the same issues, however I didn’t delete the directory. How should I go about deleting the directory (If that’s needed) And will it cause any harm to revision control or anything regarding my project? Thank you! ---
**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:** [May 10, 2025, 8:57pm UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/4 "2025-05-10T20:57:04Z")
> [@DRAW12](#): > > How should I go about deleting the directory (If that’s needed) And will it cause any harm to revision control or anything regarding my project? > > Thank you! Hi @DRAW12 . This wont affect Revision Control. You are deleting intermediate temporary files which have become “locked” to UEFN and cannot be deleted because they are protected so that only you manually delete the Apps do not have privilege do wildcard deletes on a directory you should check your disk first though ![ChkDsk picture](https://d3kjluh73b9h9o.cloudfront.net/original/4X/0/b/1/0b17a90a44204d2ace8fe68218d2fe0f72f4c1df.png) Run as Administrator c:\> chkdsk /f/r C: yes restart your PC and the disk will be checked (20 minutes) If no errors or errors have been fixed try deleting the file first ```auto C:\Users\USERNAME\AppData\Local\UnrealEditorFortnite\Intermediate\ValkyrieUploadTemp\2cd13d7f-4475-6439-71c6-f9956e9e8d9c\runic.zip ``` Normally the directory ValkyrieUploadTemp does not exist only during cooking and transfer. ---
**Author:** ![DRAW12](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/draw12/32/1062897_2.png) [@DRAW12](https://forums.unrealengine.com/u/DRAW12)\ **Post date:** [May 12, 2025, 4:57am UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/5 "2025-05-12T04:57:26Z")
So I have some questions on this and some further information I want to give: - Friends on different (Lower spec) computers were able to launch session and private version just fine. So this leads me to think you’re right on this. - I downloaded the entire project on my laptop (UEFN and Fortnite was already installed on there) to see if there were issues from there, it still gave the same exact errors. Can a download be corrupted from the same windows account on two different devices? I really appreciate your help. Do you think you could also better reference the process of what I need to do for deleting the directory? ---
**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:** [May 12, 2025, 5:59pm UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/6 "2025-05-12T17:59:58Z")
hi @DRAW12 If you have another version on a laptop and you are using Revision control. Remove your copy of the project you put on the laptop. Restore it from Unreal Revision Control to sync your project on the laptop. see the documentation. see [URC Sync changes](https://dev.epicgames.com/documentation/en-us/uefn/unreal-revision-control-in-unreal-editor-for-fortnite#sync-changes) This will bring down a new copy of your project, then you can try and run your project You don’t need to try and delete the file on the laptop. ---
**Author:** ![DRAW12](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/draw12/32/1062897_2.png) [@DRAW12](https://forums.unrealengine.com/u/DRAW12)\ **Post date:** [May 12, 2025, 9:15pm UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/7 "2025-05-12T21:15:16Z")
Hello, I had forgotten to mention that I had only used my laptop as a means of testing if the project would work on another device, aside from my desktop. For the process you mentioned, deleting my copy and syncing to latest with revision control, I have already tried this on my desktop and received the same errors. Why are my friends able to launch sessions on their computers, but I cannot launch session (Even after redownloading the project) on either of mine? ---
**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:** [May 12, 2025, 9:20pm UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/8 "2025-05-12T21:20:11Z")
Hi @DRAW12 Just seen this known problem with cooking some islands not cooking [We are investigating an issue in UEFN where some projects are failing to cook. We’ll follow up as soon as we have a fix or more information.](https://forums.unrealengine.com/t/fortnite-ecosystem-v35-00-with-known-issues/2486563/11) ---
**Author:** ![system](https://d3kjluh73b9h9o.cloudfront.net/original/4X/7/1/3/713c9d3f58553f0de89543d76a8a3a2779dc9fa4.png) [@system](https://forums.unrealengine.com/u/system)\ **Post date:** [November 6, 2025, 3:01am UTC](https://forums.unrealengine.com/t/cannot-launch-session-given-errors-that-i-cannot-fix/2499976/9 "2025-11-06T03:01:59Z")
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