[CRITICAL] Launching Session Error – “At least 1 module failed remote validation"

Summary

This issue randomly started happening happening on ALL of my projects where I am unable to launch a session. Whenever I try, it fails with the error: “At least 1 module failed remote validation.”

It has this error line in the output log:
LogValkyrie: Error: FlowStep_ResolveSessionCandidates(): Candidate module [5dcc6ed6-4cef-bae1-82af-1d9b792f2230] failed validation with error: [errors.com.epicgames.pre-processing.download_failure]

I haven’t been able to identify what is causing this. It’s also not limited to just me, I don’t think this is actually a problem on my end. Multiple people in the community are experiencing the same problem.

Previously everything was working perfectly fine but it just randomly stopped working.

I also wanted to mention that fortnite still loads but I have to push changes and my game is in the specific area you are in when you join creative 1.0 (But without the portals).
Also when I push changes I get the same error.

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Other

Steps to Reproduce

Everytime I launch session or push changes

Expected Result

My project would have it’s session launched normally

Observed Result

Error Message: “At least 1 module failed remote validation”
Output Log Error: LogValkyrie: Error: FlowStep_ResolveSessionCandidates(): Candidate module [5dcc6ed6-4cef-bae1-82af-1d9b792f2230] failed validation with error: [errors.com.epicgames.pre-processing.download_failure]

Platform(s)

PC
(Minimum requirements met for UEFN)

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Additional Notes

I saw one other thread where sombody else had the same problem and 2 staff members cleared the account cache and I think it fixed the issue so I would really appreciate if a staff member helps me on this

I really need help on this, I have to post a map very soon and playtest others

(post deleted by author)

@Flak I apologize for tagging you but I’m very desperate. I saw another thread where you helped somebody with this same problem and I was wondering if you could help me with this too

I also wanted to mention that I even tried creating a completely new project and got the same issue, but only one old project is working for some reason

FORT-1062655 has been created and its status is ‘Unconfirmed’. This is now in a queue to be reproduced and confirmed.

hi @aynjml

Please check this posting thread which has the same problems and try the potential answers to this problem

At least 1 module failed remote validation - General / Issues and Bug Reporting - Epic Developer Community Forums

At least 1 module failed remote validation on main account but not alt account. - General / Issues and Bug Reporting - Epic Developer Community Forums

(post deleted by author)

Hi, Thanks for responding

I tried everything, verified files, reinstalled UEFN, transfered the project to different teams. This randomly started to happen after an update a few days ago. The weird part is that only ONE of my projects is working while the others and even completely new ones aren’t.

I’ll try using an alt account but even if that works I’ll still be waiting for a staff member to respond because I saw a few threads where they fixed this for some people. I can’t just keep switching accounts whenever I have to work on a map

hi @aynjml

The post below says that this problem will possibly be fixed on 40.00 , 19th March 2026

see

Picture of new function in 40.00

[CRITICAL] Unable to launch session – “At least 1 module failed remote validation” - General / Issues and Bug Reporting - Epic Developer Community Forums

[CRITICAL] Unable to launch session – “At least 1 module failed remote validation” - General / Issues and Bug Reporting - Epic Developer Community Forums

This post claims to fix the problem

[CRITICAL] Unable to launch session – “At least 1 module failed remote validation” - General / Issues and Bug Reporting - Epic Developer Community Forums

1 Like

That’s great to hear, I guess I’ll wait. Thank you for helping

1 Like

I have the same issue? can you clean my account cache please?

LogValkyrie: Error: FlowStep_ResolveSessionCandidates(): Candidate module [f29e877c-4b11-e2b4-550b-6597e39d973b] failed validation with error: [errors.com.epicgames.pre-processing.download_failure]
LogValkyrieFortniteEditorLiveEdit: Verbose: FValkyrieFortniteEditorLiveEdit::UploadEnd C:/Users/Usuario/Documents/Fortnite Projects/Fortnite_Go_Up_For_All_Brainrots/Fortnite_Go_Up_For_All_Brainrots.uefnproject, Failed
LogValkyrieFortniteEditorLiveEdit: Verbose: FValkyrieFortniteEditorLiveEdit::SetUploadRequired 1
LogValkyrieFortniteEditorLiveEdit: Verbose: FValkyrieFortniteEditorLiveEdit::SetTrackingUploadRequired 0
LogValkyrieRequestManagerEditor: OnProjectSyncCompleted: C:/Users/Usuario/Documents/Fortnite Projects/Fortnite_Go_Up_For_All_Brainrots/Fortnite_Go_Up_For_All_Brainrots.uefnproject, Failed
LogValkyrieEditorAnalytics: Displaying Stats for Flow
LogValkyrieEditorAnalytics: =========================
LogValkyrieEditorAnalytics: Flow=Play
LogValkyrieEditorAnalytics: PlayFlow=231.550
LogValkyrieEditorAnalytics: ↳ PrepareProjectSourceData=9.891
LogValkyrieEditorAnalytics: ↳ UploadCookDownload=231.550
LogValkyrieEditorAnalytics: ↳ ValidationSessionInitializeContext=5.160
LogValkyrieEditorAnalytics: ↳ ValidationSessionRunLocalValidation=4.634
LogValkyrieEditorAnalytics: ↳ SyncWithContentService=0.962
LogValkyrieEditorAnalytics: ↳ UpdateProjectMetadata=0.283
LogValkyrieEditorAnalytics: ↳ InitSyncModules=1.314
LogValkyrieEditorAnalytics: ↳ StageProjectModules=0.354
LogValkyrieEditorAnalytics: ↳ GatherFilesForValidation=0.000
LogValkyrieEditorAnalytics: ↳ DownloadPublishedVerseFiles=0.000
LogValkyrieEditorAnalytics: ↳ ValidateProject=1.415
LogValkyrieEditorAnalytics: ↳ FindServer=214.305
LogValkyrieEditorAnalytics: ↳ MatchmakingToServer=212.576
LogValkyrieEditorAnalytics: ↳ ValidationSessionUploadCandidateSourceFiles=4.760
LogValkyrieEditorAnalytics: ↳ ValidationSessionCreateValidationSession=0.256
LogValkyrieEditorAnalytics: ↳ ValidationSessionCreateModuleVersions=216.386
LogValkyrieEditorAnalytics: ↳ ValidationSessionPruneScratchSpace=216.386
LogValkyrieEditorAnalytics: ↳ ValidationSessionResolveSessionCandidates=0.231
LogValkyrieEditorAnalytics: =================================

The option is available in uefn now, click “help” on the top of uefn then click clear source files cache

1 Like

It works! Thank you. You’re the goat!