# Blocker - UEFN unable to Launch Session as of latest update

**URL:** <https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497>\
**Category:** Issues and Bug Reporting\
**Tags:** fortnite-creative, unreal-editor-for-fortnite, fortnite\
**Created:** [August 17, 2024, 12:19am UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497 "2024-08-17T00:19:02Z")\
**Posts on this page:** 11\
**Page:** 1

<div class="post-metadata">

**Author:** ![wabisabisoup](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@wabisabisoup](https://forums.unrealengine.com/u/wabisabisoup)\
**Post date:** [August 17, 2024, 12:19am UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/1 "2024-08-17T00:19:02Z")

</div>

### Please select what you are reporting on:

Unreal Editor for Fortnite

### What Type of Bug are you experiencing?

Other

### Summary

Unable to launch Session after latest update

When I click the “Launch Session” button in UEFN, one out of three things happen:

1. Fortnite shows up a loading screen, after which I’m being returned back to the Launcher. In UEFN, it shows as “Session Connected”, but Fortnite didn’t load anything.
2. I get a “Connection Error” in Fortnite, and the Session is canceled.
3. My Island is opened in Fortnite, but there are no Assets loaded, and when trying to exit the Session, the game freezes, requiring me to force quit Fortnite using the Task Manager.

This is a major issue blocking me from working on my current project.

### Steps to Reproduce

Click “Launch Session” and observe that, in fact, the Session does not launch.

### Expected Result

“Launch Session” successfully launches a Session.

### Observed Result

“Launch Session” does not launch a Session.

### Platform(s)

PC

### Additional Notes

Excerpt from the Output Log:

LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/STW/STW\_Irwin/STW\_Irwin.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogValkyrieAccount: [UValkyrieOnlineInstance::ApplyUserPreferredQoSRegion] Region Auto: ASIA  
LogSlate: Warning: Slate: Had to block on waiting for a draw buffer  
LogOnlineSession: Warning: MCP: FindSingleSession request failed. Invalid response. code=404 error={  
“errorCode” : “errors.com.epicgames.modules.matchmaking.unknown\_session”,  
“errorMessage” : “unknown session id 2b75b61b7ac944e6b45bed68d1206df4”,  
“messageVars” : [“2b75b61b7ac944e6b45bed68d1206df4”],  
“numericErrorCode” : 12101,  
“originatingService” : “fortnite”,  
“intent” : “prod-live”  
}  
LogOnline: Warning: OSS: Async task ‘FOnlineAsyncTaskMcpFindSingleSession bWasSuccessful: 0’ failed in 0.242982 seconds

---

<div class="post-metadata">

**Author:** ![VortexCAKO](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@VortexCAKO](https://forums.unrealengine.com/u/VortexCAKO)\
**Post date:** [August 17, 2024, 6:44pm UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/2 "2024-08-17T18:44:43Z")

</div>

I have the same problem.

```auto
LogValkyrieSummary: No active session for current user. Creating new session.
LogValkyrie: Play succeeded.
LogSlate: Warning: Slate: Had to block on waiting for a draw buffer
LogValkyrie: ProjectSizeRequest for ef802c66-44d1-7c14-50ca-118ea16ca38d: GetProjectContentPackage
LogValkyrie: ProjectSizeRequest::GetProjectUploadSize for ef802c66-44d1-7c14-50ca-118ea16ca38d
LogValkyrie: ProjectSizeRequest::GetProjectDownloadSize for ef802c66-44d1-7c14-50ca-118ea16ca38d
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/STW/STW_Irwin/STW_Irwin.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogValkyrieAccount: [UValkyrieOnlineInstance::ApplyUserPreferredQoSRegion] Region Auto: NAE
LogValkyrie: ProjectSizeRequest::Cancel for ef802c66-44d1-7c14-50ca-118ea16ca38d - Content (re)cook error errors.com.epicgames.pre-processing.failed.
JOB_ID=850156e6-6a80-453a-9c27-5a7ca8c6174f
LogOnlineSession: Warning: MCP: FindSingleSession request failed. Invalid response. code=404 error={
  "errorCode" : "errors.com.epicgames.modules.matchmaking.unknown_session",
  "errorMessage" : "unknown session id 2b62af305600482f8d98a3f4661ae316",
  "messageVars" : ["2b62af305600482f8d98a3f4661ae316"],
  "numericErrorCode" : 12101,
  "originatingService" : "fortnite",
  "intent" : "prod-live"
}
LogOnline: Warning: OSS: Async task 'FOnlineAsyncTaskMcpFindSingleSession bWasSuccessful: 0' failed in 0.065969 seconds
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/STW/STW_Irwin/STW_Irwin.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogGameFeatures: Error: Dependency file:../../../FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin_Missing_GameFeatureData
LogValkyrieAccount: [UValkyrieOnlineInstance::ApplyUserPreferredQoSRegion] Region Auto: NAE
LogNet: Warning: Channel name will be serialized as a string: ValkyrieBeacon
LogValkyrieSummary: Valkyrie Beacon Connected!
LogValkyrieSummary: Connected to Session: 390ce02acdf24e36925665670f07c1b6
LogValkyrieSummary: Session Setup Complete. About to Send Content!
LogValkyrieSummary: Checking for if the project can be uploaded
LogValkyrieSummary: Starting Project Upload - https://content-service.bfda.live.use1a.on.epicgames.com/project/#/4639a73b-41e1-bfc0-cb3d-a5abcc162768
LogValkyrieSummary: Syncing project MyFirstProject
LogSlate: Warning: Slate: Had to block on waiting for a draw buffer
LogValkyrie: Saving project source control settings to disk took 0.00 sec
LogValkyrie: Syncing project MyFirstProject with content service took 0.49 sec
VerseBuild: Warning: C:/Users/18182/Documents/Fortnite Projects/MyFirstProject/Plugins/MyFirstProject/Content/Code/zone_manager_device.verse(238,9, 249,1): Script warning 2000: Unreachable code - previous expression is guaranteed to exit early.
VerseBuild: Warning: C:/Users/18182/Documents/Fortnite Projects/MyFirstProject/Plugins/MyFirstProject/Content/Code/zone_manager_device.verse(238,9, 249,1) : Script warning 2000: Unreachable code - previous expression is guaranteed to exit early.
LogValkyrieSummary: Starting to upload file for module creation
LogValkyrieSummary: Successfully created module
LogValkyrieSummary: Creating Module Version
LogValkyrieSummary: Sending Content Update
LogValkyrieSummary: Calling UpdateContent on Valkyrie beacon with: ProjectId(4639a73b-41e1-bfc0-cb3d-a5abcc162768) SnapshotId(9a94edca-2f92-4257-b7c9-59992c960947) ModuleId(ef802c66-44d1-7c14-50ca-118ea16ca38d) ModuleVersion(955)
LogValkyrieSummary: RPCing content cook request to server: ProjectId(4639a73b-41e1-bfc0-cb3d-a5abcc162768) SnapshotId(9a94edca-2f92-4257-b7c9-59992c960947)
LogValkyrieSummary: Project MyFirstProject up to date
LogValkyrie: ProjectSizeRequest::Prepare for ef802c66-44d1-7c14-50ca-118ea16ca38d
LogValkyrie: ProjectSizeRequest for ef802c66-44d1-7c14-50ca-118ea16ca38d: GetRootModuleInfo
LogValkyrie: ProjectSizeRequest for ef802c66-44d1-7c14-50ca-118ea16ca38d: GetProjectContentPackage
LogValkyrie: ProjectSizeRequest::GetProjectUploadSize for ef802c66-44d1-7c14-50ca-118ea16ca38d
LogValkyrie: ProjectSizeRequest::GetProjectDownloadSize for ef802c66-44d1-7c14-50ca-118ea16ca38d
LogValkyrie: ProjectSizeRequest::Cancel for ef802c66-44d1-7c14-50ca-118ea16ca38d - Content (re)cook error errors.com.epicgames.pre-processing.failed.
JOB_ID=850156e6-6a80-453a-9c27-5a7ca8c6174f
LogValkyrieSummary: Server Summary - Successfully activated content on all platforms

```

---

<div class="post-metadata">

**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:** [August 18, 2024, 6:34am UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/3 "2024-08-18T06:34:48Z")

</div>

> [@VortexCAKO](#):
>
> V**erseBuild: Warning: C:/Users/18182/Documents/Fortnite Projects/MyFirstProject/Plugins/MyFirstProject/Content/Code/zone\_manager\_device.verse(238,9, 249,1): Script warning 2000: Unreachable code - previous expression is guaranteed to exit early**.  
> VerseBuild: Warning: C:/Users/18182/Documents/Fortnite Projects/MyFirstProject/Plugins/MyFirstProject/Content/Code/zone\_manager\_device.verse(238,9, 249,1) : Script warning 2000: Unreachable code - previous expression is guaranteed to exit early.

This is some sort of Verse error in the zone\_manager\_device.verse. line 238 to 249 You will need to go into Verse and compile again. Delete Zone\_Manager\_device code and compile again

---

<div class="post-metadata">

**Author:** ![VortexCAKO](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@VortexCAKO](https://forums.unrealengine.com/u/VortexCAKO)\
**Post date:** [August 18, 2024, 7:45pm UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/4 "2024-08-18T19:45:09Z")

</div>

Thats not an error, that’s just a warning due to an early return with some code I didn’t comment out.

I still have this problem.

---

<div class="post-metadata">

**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:** [August 19, 2024, 1:26am UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/5 "2024-08-19T01:26:48Z")

</div>

The status of FORT-780313 incident has been moved from ‘Needs Triage’ to ‘Closed’. Resolution Reason: ‘Cannot Reproduce’

---

<div class="post-metadata">

**Author:** ![KKGEdison](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@KKGEdison](https://forums.unrealengine.com/u/KKGEdison)\
**Post date:** [August 22, 2024, 3:03pm UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/6 "2024-08-22T15:03:08Z")

</div>

I have the same issue. Have you found any solutions?

---

<div class="post-metadata">

**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:** [August 22, 2024, 11:39pm UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/7 "2024-08-22T23:39:08Z")

</div>

hi @VortexCAKO ,  
You have done this before but can you try [Verify UEFN/Fortnite](https://forums.unrealengine.com/t/urc-exe-and-urc-dll-get-flagged-as-malware-from-microsoft-defender/1802519/5) again

If there are any updates they will be applied as well

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<div class="post-metadata">

**Author:** ![SayRunOsiris](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/sayrunosiris/32/727752_2.png) [@SayRunOsiris](https://forums.unrealengine.com/u/SayRunOsiris)\
**Post date:** [August 26, 2024, 10:26pm UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/8 "2024-08-26T22:26:34Z")

</div>

Verifying UEFN/Fortnite and a clean uninstall reinstall did not fix it for me.

I was able to get through it by opening and launching a session from a different project, then re-opening and launching the original, problematic project.

Hopefully this helps others!

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<div class="post-metadata">

**Author:** ![xXBig-CheeseXx](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@xXBig-CheeseXx](https://forums.unrealengine.com/u/xXBig-CheeseXx)\
**Post date:** [September 3, 2024, 4:45am UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/9 "2024-09-03T04:45:25Z")

</div>

can you help me with what this error means?

LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/STW/STW\_Irwin/STW\_Irwin.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData  
LogGameFeatures: Error: Dependency file:…/…/…/FortniteGame/Plugins/GameFeatures/SaveTheWorld/SaveTheWorld.uplugin failed to transition with error GameFeaturePlugin.StateMachine.Registering.Plugin\_Missing\_GameFeatureData

---

<div class="post-metadata">

**Author:** ![Tofuszn](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/tofuszn/32/1019707_2.png) [@Tofuszn](https://forums.unrealengine.com/u/Tofuszn)\
**Post date:** [November 25, 2024, 5:27am UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/11 "2024-11-25T05:27:51Z")

</div>

did you figure out how to fix this?

I am having the same problem…

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<div class="post-metadata">

**Author:** ![superspark25](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@superspark25](https://forums.unrealengine.com/u/superspark25)\
**Post date:** [January 24, 2025, 10:45am UTC](https://forums.unrealengine.com/t/blocker-uefn-unable-to-launch-session-as-of-latest-update/1979497/12 "2025-01-24T10:45:59Z")

</div>

solved my issue thanks