When I try to launch session after the latest update (36.20) on this project it keeps giving an error “Failed to validate module candidate versions”. I tried to delete some of the assets that show up in the output log error but that didn’t change the error. I can’t launch session at all.
UPDATE: Removing all the assets showing in the error log and their references let us launch session, but we still don’t know why those assets were a problem and removing them isnt really a long term solution.
I’d also like to add that I have tried a lot to get around this. There are no errors listed in message log, only output log. Editor Loads Project in Slow. Cannot Launch a Session. Ended up Reverting Back to Older Snapshot so I could make an update, but cannot build new hlods so progress is really at a hault. Everything was fine until a couple weeks ago. Fixing Redirectors helped a ton with load in time for UEFN Editor, so that is a plus.
Deleted Hlods, Replaced Hlods References. Every time it appears to work, but when I went into the project folder on my D: Drive, the old hlod ueassets were still listed there. I did “Fixed Redirectors” by right clicking the project content folder in uefn and it removed them. Loads in Much Faster. Still Get Issue with Error when Trying to Launch..
Re-Validated UEFN and Fortnite, Ran in Administrator and without Administrator.
Deleted project from computer and synced it back using Revision Control.
In my session its related to a material instance of the Custom Creative landscape and adding it to custom meshes. It also might be related to their use with data layers. This is a consistent repeating bug. I rolled back to leave this bug behind but it came back on the same assets when messing with data layers.
Also note this asset was created with modeling mode and not an import.
Before this update these static mesh assets were stable for 4 months.
Turn on view HLODs in the Outliner via the Editor Preferences
type HLOD in the outliner filter.
There are a couple of rogue props generating HLOD layers, but because they are not referenced by your project it makes them invalid.
Any HLOD references there that are not your HLOD layer name are either your old HLOD layer empty(or full) folders or they are being generated by certain Fortnite props.
For instance if you are using a few types of Asteria Trees and most of the Signs from Mega City you will see AsteriaTreeHLODLayer and NeoncityblahblahHLOD or something greyed out.
Select These and Force Load, then double click on them to see which props they are the HLODs for
Next drag your HLODLayer into each props Default HLOD layer slot.
This will override it and make it use your HLODLayer
When your finshed DeleteHLODs from the Build menu and manually delete all the HLOD folders in the outliner, double click your level thumbnail to reload map and BuildHLODs
Repeat if you didn’t get them all first go
I think its completely random as yesterday it works then it didnt and now today its not working again idk what they did but something is drastically wrong
When you validate do you get the all projects upto data with green tick ? i get this which would suggest its all valid ect yet when i launch session after waiting maybe 4 mins i get the error is it same for you ?
Also getting the same error messages re module error when trying to launch a session, only started today (CET) was fine last night.
I’ve been going through the logs trying to find references to anything in the level, could only find a reference to a “dance mannequin” so have deleted those 3 props.
Log was getting spammed with this so much the editor kept freezing also:
[2025.07.20-10.28.30:262][245]LogFortCosmetics: Warning: AnimMontage Provided was null. We require a valid montage to process!
[2025.07.20-10.28.30:293][246]LogAnimation: Warning: AnimDynamics: Min/Max angular limits for bone dyn_bracelet_01_l incorrect, at least one min axis value is greater than the corresponding max.
i have exactly the same issue.
Nothing in the log except this message :
Error: FlowStep_ResolveSessionCandidates(): Candidate module [59cb1356-4e81-e9da-1f38-2e86d5f63706] failed validation with error: [http_error_502:valkyrie-cook-api.prod.ucs.on.epicgames.com]
Worked perfectly yesterday and today i can’t launch a session…
Its nothing were doing wrong its something on epics backend as i just created the ui template island and this also fails and this is epics own template so i suggest not messing with your projects and they will fix it
