Unreal Engine Issues and Bug Tracker (UE-145921)

Description

The following cook error results from attempting to package a WP map that has level instances using level BPs:

LogCook: Error: PackageSplitter found the Generator package still in
memory after it should have been deleted by GC.
UATHelper: Cooking (Windows): This is unexpected since garbage has been collected and the package
should have been unreferenced so it should have been collected, and will break population of
Generated packages.

Steps to Reproduce

Create a non-wp map, add a variable to the level BP, and then enable external actors via World Settings.
Open a WP map, add a level instance actor using the newly created non-wp level.
Create a packaged build.

Callstack

LogWindows: Error: begin: stack for UAT
LogWindows: Error: === Critical error: ===
LogWindows: Error:
LogWindows: Error: Assertion failed: FindObject<UPackage>(nullptr, *InPackage->GetName()) [File:F:\Build\UE5-Main\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionLevelHelper.cpp] [Line: 170]
LogWindows: Error:
LogWindows: Error:
LogWindows: Error:
LogWindows: Error: [Callstack] 0x00007ffb7c14019f UnrealEditor-Engine.dll!FWorldPartitionLevelHelper::CreateEmptyLevelForRuntimeCell() [F:\Build\UE5-Main\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionLevelHelper.cpp:170]
LogWindows: Error: [Callstack] 0x00007ffb7c1bad86 UnrealEditor-Engine.dll!UWorldPartitionRuntimeLevelStreamingCell::PopulateGeneratedPackageForCook() [F:\Build\UE5-Main\Engine\Source\Runtime\Engine\Private\WorldPartition\WorldPartitionRuntimeLevelStreamingCell.cpp:206]
LogWindows: Error: [Callstack] 0x00007ffb785d97e0 UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TryPopulateGeneratedPackage() [F:\Build\UE5-Main\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:2642]
LogWindows: Error: [Callstack] 0x00007ffb785b173d UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::LoadPackageInQueue() [F:\Build\UE5-Main\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:2242]
LogWindows: Error: [Callstack] 0x00007ffb785bf87e UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::PumpLoads() [F:\Build\UE5-Main\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:2094]
LogWindows: Error: [Callstack] 0x00007ffb785d78fb UnrealEditor-UnrealEd.dll!UCookOnTheFlyServer::TickCookOnTheSide() [F:\Build\UE5-Main\Engine\Source\Editor\UnrealEd\Private\CookOnTheFlyServer.cpp:1203]
LogWindows: Error: [Callstack] 0x00007ffb783965d9 UnrealEditor-UnrealEd.dll!UCookCommandlet::CookByTheBook() [F:\Build\UE5-Main\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:1010]
LogWindows: Error: [Callstack] 0x00007ffb783b84bc UnrealEditor-UnrealEd.dll!UCookCommandlet::Main() [F:\Build\UE5-Main\Engine\Source\Editor\UnrealEd\Private\Commandlets\CookCommandlet.cpp:688]
LogWindows: Error: [Callstack] 0x00007ff795b38ec1 UnrealEditor-Cmd.exe!FEngineLoop::PreInitPostStartupScreen() [F:\Build\UE5-Main\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:3672]
LogWindows: Error: [Callstack] 0x00007ff795b30a2d UnrealEditor-Cmd.exe!GuardedMain() [F:\Build\UE5-Main\Engine\Source\Runtime\Launch\Private\Launch.cpp:140]
LogWindows: Error: [Callstack] 0x00007ff795b30cfa UnrealEditor-Cmd.exe!GuardedMainWrapper() [F:\Build\UE5-Main\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:147]
LogWindows: Error: [Callstack] 0x00007ff795b33b6d UnrealEditor-Cmd.exe!LaunchWindowsStartup() [F:\Build\UE5-Main\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:283]
LogWindows: Error: [Callstack] 0x00007ff795b445d4 UnrealEditor-Cmd.exe!WinMain() [F:\Build\UE5-Main\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:330]
LogWindows: Error: [Callstack] 0x00007ff795b46912 UnrealEditor-Cmd.exe!__scrt_common_main_seh() [d:\a01\_work\6\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
LogWindows: Error: [Callstack] 0x00007ffc04ab7034 KERNEL32.DLL!UnknownFunction []
LogWindows: Error: [Callstack] 0x00007ffc065a2651 ntdll.dll!UnknownFunction []
LogWindows: Error:
LogWindows: Error: end: stack for UAT

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Unresolved

Component	UE - World Creation - Worldbuilding Tools - Level Instances
Affects Versions	5.1
Target Fix	5.5

Created	Mar 14, 2022
Updated	Feb 13, 2024

UE-145921

Cook failure when World Partition maps have level instances using level blueprints

Cook failure when World Partition maps have level instances using level blueprints

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