Fatal error "because the supplied package name was neither a valid long package name nor a filename of a map within a content folder"

Exactly what it says on the tin. I get this error whenever I try to boot my game, even though it packaged and cooked successfully, and I have no idea what it’s saying or how to fix it. Very new to this… quick responses would be very much appreciated. I spent ages on this game and just want it out the door in the next few hours.

Fatal error: [File:D:\Build++UE4+Release-4.16+Compile\Sync\Engine\Source\Runtime\Core\UObject\Private\Serialization\AsyncLoading.cpp] [Line: 6409] LoadPackageAsync failed to begin to load a package because the supplied package name was neither a valid long package name nor a filename of a map within a content folder: "

217775-capture.jpg

Same here, version 4.17.2.
The game works when launch in editor or outside… however after packaged it crashes like this:
Error: === Critical error: ===
[2017.10.24-20.17.58:234][ 1]LogWindows: Error:
[2017.10.24-20.17.58:234][ 1]LogWindows: Error: Fatal error: [File:D:\Build++UE4+Release-4.17+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading.cpp] [Line: 6592]
[2017.10.24-20.17.58:234][ 1]LogWindows: Error: LoadPackageAsync failed to begin to load a package because the supplied package name was neither a valid long package name nor a filename of a map within a content folder: ‘’

Same exact thing here, with Unreal 4.16.3.

Wait, so why is this happening for everyone? Is this a glitch? Can anyone publish projects? Or is there a problem all of our projects share?

I figure this out.

In my case, inside GameInstance class, when browsing URL like this: BrowseRet = GetEngine()->Browse(*WorldContext, URL, Error); I used to construct the URL using only the map name… now I have to use the whole path like “/Game/Maps/NameOfTheMap”

I’m sorry, I’m very new to this and don’t understand what you said…

The thing is that somewhere in your code you may asking some resource that can’t be found.

In my case, I had inside my UGameInstance class a function call to travel to a map. The call is this one: GetEngine()->Browse(*WorldContext, URL, Error), note that this URL was built by using the name of the map, like so: FURL URL(*FString::Printf(TEXT(“MapName”)));

In older versions of the UE4 it worked perfectly, in earlier versions I have to construct this URL using the whole path to the map, like this: FURL URL(*FString::Printf(TEXT("/Game/Maps/MapName")));

I hope it helps.

We always used the full path for maps, but also faced this problem.
By the way, that error happens only with the multiplayer game. In the solo mode, everything works fine.

Currently having this problem in a multiplayer game in 4.18.3, using the LoadFrontEndMap functionality from the ShooterGame example in our project. The URL is constructed of the full path name, but still having issues. Our map is located in “/Game/ProjectName/Maps/MapNameFolder/MapName”. Tried all sorts of thing over the past 48 hours and still no progress. Anyone get around this?
It clearly recognises the map name as when it crashes, the log shows the cutdown name it found which is just “MapName” which it attempts to load and runs in to this error

Did you ever find a solution to this?

No. I think it’s beyond my abilities as someone who just picked up the software mid last year.

That’s fair, I’m a programmer who has worked with the engine for almost 4 years and I’m struggling to resolve this! It does almost feel like this is an engine glitch/the debug log isn’t giving enough information