Build failed in 4.18: LNK1181 on UE4-LoginFlow.lib

Hi there,

My project uses Steam Online Subsystem. Compiled/packaged just fine in 4.16, but now in 4.18 I get the following error when packaging for Windows 64-bit:

UATHelper: Packaging (Windows (64-bit)): [4/4] Link MyProject.exe
UATHelper: Packaging (Windows (64-bit)): LINK : fatal error LNK1181: cannot open input file ‘W:\Games_W\UE4-418\UE-4.18\Engine\Plugins\Online\OnlineFramework\Binaries\Win64\UE4-LoginFlow.lib’
UATHelper: Packaging (Windows (64-bit)): ERROR: UBT ERROR: Failed to produce item: W:\UE4_PROJECTS_NEW\MyProject\Binaries\Win64\MyProject.exe

I looked in that folder linked above and there’s no UE4-LoginFlow.lib file there. Though there is a UE4Editor-LoginFlow.dll. Looking through previous versions of UE4, I can’t find this .lib file there either, but it doesn’t seem to cause any errors on those versions. Is it a new 4.18 thing?

I tried verifying my 4.18 install, and tried copying all my assets to a new blank project. Still the same issue. The only plugins I am using are Online Subsystem, OnlineSubsystem Steam, and all the associated plugins for that.

Any ideas on what the issue might be? I’d like to keep this project in 4.18 to take advantage of all the neat stuff that came out with it.

By the way, if I disable online subsystem completely, the game builds fine. Has something to do with online subsystem framework.

I got the same thing and trying to debug it now. I will keep an eye on this thread and see if you find how to fix it :slight_smile:

Sounds good! Keep me posted if you find a solution…I’m gonna try making a new fresh project tonight and adding online subsystem plugins and see if that works. I’m pretty sure it will still fail though – I think I am somehow missing a key .lib file here. Next step would be to completely uninstall and reinstall 4.18…

If it’s helpful at all, here is my full log for the build attempt:

Can’t seem to find anything in here that helps my case out much, however…

Well, I think I fixed it.

I had the plugin “Online Framework Plugin” ticked. I thought it was required by the main Online Subsystem plugin, like Online Subsystem Utils. Turns out, however, it is not required to run Steam, at least.

So I disabled that plugin, restarted the editor, and it all appears to work now. The game communicates with Steam and gets the overlay. Haven’t tried creating/joining sessions yet – gonna do that next. But it appears to build now, at least!

Hope this is helpful to someone who runs into the same issue – I wonder, then, what is the proper use of Online Framework Plugin, if it crashes builds instantly?

Just in case you didn’t see – I found a solution, check below!

Thanks for the update. I found that it also was the online framework i had problems with. At some point i did toy around with their party system, but ended up not using it, so i could disable it too.
It still sucks not being able to use their party/lobby/loginflow systems, but i guess i will have to look at it again if we choose to use it.
For me sessions and Steam online works fine as before the 4.18 update.

This isn’t a fix - many users still require the Online Framework plugin to be active.

Some of my own plugins have dependencies on it, this definitely feels like a bug to me.

Interesting. Have you found out anything new on the subject? I’d like to be able to re-enable Online Framework to use those features…