"Failed to resolve validation session" when launching session, doesn't point out any errors or files

Summary

When I try to launch the session, specifically during “Creating Modules” i get a “Failed to resolve validation session” error. There aren’t any files or errors shown in the Message Log, but here’s what the Output Log says during the error:

LogValkyrie: Error: FlowStep_ResolveSessionCandidates(): Failed to resolve validation session with error [{
“host”: “content-service.bfda.live.use1a.on.epicgames.com”,
“method”: “GET”,
“path”: “/api/content/v4/validation/session/71215862-3b59-4a82-ac80-8a87ac056dd8/resolve”,
“errorCode”: “errors.com.epicgames.content-service.module_validation_session_invalid_operation”,
“errorMessage”: “session 71215862-3b59-4a82-ac80-8a87ac056dd8 cannot be resolved until all candidate validations have been trigerred”
}]
LogOutputDevice: Warning: Script Stack (0 frames) :
LogOutputDevice: Error: === Handled ensure: ===
LogOutputDevice: Error: Ensure condition failed: Task == this [File:Z:\UEVFS\Root\Engine\Source\Runtime\Core\Private\Misc\SlowTask.cpp] [Line: 149]
LogOutputDevice: Error: Out-of-order slow task construction/destruction: destroying ‘Uploading Projects…’ but ‘Matchmaking …’ is at the top of the stack
LogOutputDevice: Error: Stack:
LogOutputDevice: Error: [Callstack] 0x00007ff7891cbd22 UnrealEditorFortnite-Win64-Shipping.exe!UnknownFunction

It should be mentioned that there are more people experiencing this issue, not just me: Starting Session in UEFN impossible | Validation Error

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Matchmaking

Steps to Reproduce

Start the session

Expected Result

Session starts normally

Observed Result

“Failed to resolve validation session” Error

Platform(s)

PC