Packaging Error when Project is updated from 5.4&5.5 to 5.6.1?

XilenceX · September 11, 2025, 3:54pm

Our project packaging works fine in version 5.4 which we currently use and in 5.5.
However once I upgrade it to 5.6.1 it breaks with the errors listed below.

We are using UE 5.4 MetaHumans, could that be an issue?

The lines before the error appears are
UATHelper: Packaging (Windows): LogSkeletalMesh: Display: Waiting for skinned assets to be ready 0/1 (Prescott_FaceMesh) …
UATHelper: Packaging (Windows): LogSkeletalMesh: Display: Waiting for skinned assets to be ready 0/1 (m_tal_nrw_body) …

Then garbage collection is triggered because of low memory,
Then the errors below appear.

The errors themselves.
UATHelper: Packaging (Windows): LogWindows: Error: begin: stack for UAT
UATHelper: Packaging (Windows): LogWindows: Error: === Critical error: ===
UATHelper: Packaging (Windows): LogWindows: Error:
UATHelper: Packaging (Windows): LogWindows: Error: Fatal error!
UATHelper: Packaging (Windows): LogWindows: Error:
UATHelper: Packaging (Windows): LogWindows: Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff
UATHelper: Packaging (Windows): LogWindows: Error:
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff835ad64aa UnrealEditor-CoreUObject.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff835d14a0e UnrealEditor-CoreUObject.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff835e0aeab UnrealEditor-CoreUObject.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff835af1b51 UnrealEditor-CoreUObject.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff835ae8df1 UnrealEditor-CoreUObject.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff835ae862d UnrealEditor-CoreUObject.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff8097bf88e UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff8097c04f9 UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff8097c5057 UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff80974d981 UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff8095267fc UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff80956994d UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff80952a69a UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff809546c83 UnrealEditor-UnrealEd.dll!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff68a248fa0 UnrealEditor-Cmd.exe!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff68a23e39c UnrealEditor-Cmd.exe!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff68a23e6ba UnrealEditor-Cmd.exe!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff68a24209e UnrealEditor-Cmd.exe!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff68a254e44 UnrealEditor-Cmd.exe!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff68a257466 UnrealEditor-Cmd.exe!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error: [Callstack] 0x00007ff89b1ce8d7 KERNEL32.DLL!UnknownFunction
UATHelper: Packaging (Windows): LogWindows: Error:
UATHelper: Packaging (Windows): LogWindows: Error: end: stack for UAT

Finally, I have attached the full log file in case that helps.
Any help with fixing this would be greatly appreciated!

Log.txt (120.5 KB)

brs-sebascova · September 11, 2025, 6:16pm

Hello there @XilenceX!

Thank you for sending the full log. After checking through it, the main conflict remains the one you already isolated, which is the project running out of memory, and triggering the garb collector:

LogCook: Display: Garbage collection triggered (Full). 
CookSettings.MemoryMinFreeVirtual: Available virtual memory 1353MiB is less than 2048MiB.

MetaHumans were updated heavily in 5.6, so it is possible that the engine is having difficulties dealing with the 5.4 models. It can also be related to migration data not being necessary for the project, clogging up processes. Considering what we have, please test the following:

First, let’s force a clean cache for your project, via closing UE, and deleting folders Binaries, DerivedDataCache, Intermediate, Saved, and .vs from your main directory. After that, right-click your .uproject file and choose “Generate Visual Studio Project Files”, followed by “Switch Unreal Engine Version” to 5.6.1. Finally, re-open the project and allow it to recompile (it will take a while)
Next, we can update your MetaHumans, via re-download your characters, and re-import them into your project
We can also increate virtual memory to avoid the crash. Simply increase the size of your Windows page file to a larger value, on the drive where your project is located
And to rule out issues tied to the project itself, make a test by packaging a blank project. If that works, slowly migrate your project’s content into the new one, to identify what element is causing the problem

XilenceX · September 11, 2025, 9:20pm

Thanks for your response!

So here’s what I’ve tried:

Force clean cache by deleting the mentioned folders.
(It’s not a C++ project so .vs and genereate visual studio project files aren’t a thing, but did everything else.)

I installed +32GB (from old PC) to now have 64GB RAM. My page file is already at 230GB so not much I can change there.

I tried packaging an empty UE 5.6 project which worked perfectly fine.

I would love to Update our metaHumans to 5.6. as a test!
Just not sure how? MetaHuman Creator only supports up to UE 5.5.. So I guess can’t download 5.6 version from there?

PS: I’ve attached the new Log.txt. It’s.. different. But UE 5.6 still eats up the memory super quickly and then obviously will run out of memory.
At the same time only like 30GB of my 230GB pagefile ever get used before packaging fails.
Before it was a case of I had 32 GB Ram and like 60GB of the page file got used.
So it’s sort of a same difference scenario.

Log.txt (152.2 KB)

brs-sebascova · September 12, 2025, 4:54pm

Hello again!

Thanks for your update, knowing that cooking on an empty project works fine is great news. Now we know the issue is tied to the current project only. As for your new logs, I think the issue still remains the same, memory is running out, even with the extension applied.

You can see the engine forcing garbage collection once free virtual memory goes below 2GB, here:

LogMemory: Warning: Free virtual memory fell below 2048 MB (2003 MB remaining). Forcing garbage collection.
LogMemory: Display: Free virtual memory after GC: 1987 MB

Eventually, the cook dies due running out of memory, here:

LogWindows: Error: Ran out of virtual memory, tried to allocate …

There are also assets flagged as deprecated or in need of a re-save, which will further strain the process, here:

LogMetaSound: Warning: Node (MetasoundEditor.Graph.Node) is deprecated and should be updated
LogAssetTools: Asset ‘/Game/MetaSounds/…’ needs resave

The final crash remains an access violation at cook time, due the memory issue:

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address …

So, considering you have already cleared the cache, the next step here would be to resolve the deprecated/unsaved assets.

First, open the project and go to File > Resave All, so all the unsaved assets are resolved. As for MetaHumans, if you check Bridge in UE5.6, the option to re-download your characters should be there. More information on this regard can be found here:

Finally, to make the cook more manageable for your system, you can test by cooking in data chunks, using the Asset Manager, as seen in the UE documentation below:

Hope this helps!