Caused by CL# 3356347 which removed one of the arguments to the printf but did not remove a %s
When cooking QAGame (QA-Blueprints map) an assert is triggered during the cook step.
So far I have reproduced this for: Win64 and PS4.
RunUAT BuildCookRun -project=QAGame -nop4 -maps=QA-Blueprints -build -cook -stage -platform=Win64 -clientconfig=Development -nativizeassets
Result: Assert during the cook
Cook: LogWindows:Error: === Critical error: === Cook: LogWindows:Error: Cook: LogWindows:Error: Fatal error! Cook: LogWindows:Error: Cook: LogWindows:Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x0000002e Cook: LogWindows:Error: Cook: LogWindows:Error: ucrtbase.DLL!0x00000000ED7E90C1 Cook: LogWindows:Error: ucrtbase.DLL!0x00000000ED7DBC1E Cook: LogWindows:Error: ucrtbase.DLL!0x00000000ED7DB395 Cook: LogWindows:Error: UE4Editor-Core.dll!FString::Printf__VA() [d:\gh\gh4.16\engine\source\runtime\core\private\containers\string.cpp:1181] Cook: LogWindows:Error: UE4Editor-BlueprintCompilerCppBackend.dll!FString::Printf<wchar_t const * __ptr64,wchar_t const * __ptr64,wchar_t const * __ptr64,wchar_t const * __ptr64,wchar_t const * __ptr64>() [d:\gh\gh4.16\engine\source\runtime\core\public\containers\unrealstring.h:1366] Cook: LogWindows:Error: UE4Editor-BlueprintCompilerCppBackend.dll!FBackendHelperUMG::EmitWidgetInitializationFunctions() [d:\gh\gh4.16\engine\source\developer\blueprintcompilercppbackend\private\blueprintcompilercppbackendumg.cpp:97] Cook: LogWindows:Error: UE4Editor-BlueprintCompilerCppBackend.dll!FEmitDefaultValueHelper::GenerateCustomDynamicClassInitialization() [d:\gh\gh4.16\engine\source\developer\blueprintcompilercppbackend\private\blueprintcompilercppbackendvaluehelper.cpp:1622] Cook: LogWindows:Error: UE4Editor-BlueprintCompilerCppBackend.dll!FBlueprintCompilerCppBackendBase::GenerateCodeFromClass() [d:\gh\gh4.16\engine\source\developer\blueprintcompilercppbackend\private\blueprintcompilercppbackendbase.cpp:427] Cook: LogWindows:Error: UE4Editor-KismetCompiler.dll!FKismetCompilerContext::CompileFunctions() [d:\gh\gh4.16\engine\source\editor\kismetcompiler\private\kismetcompiler.cpp:4047] Cook: LogWindows:Error: UE4Editor-UMGEditor.dll!FUMGEditorModule::Compile() [d:\gh\gh4.16\engine\source\editor\umgeditor\private\umgeditormodule.cpp:160] Cook: LogWindows:Error: UE4Editor-KismetCompiler.dll!FKismet2CompilerModule::CompileBlueprintInner() [d:\gh\gh4.16\engine\source\editor\kismetcompiler\private\kismetcompilermodule.cpp:119] Cook: LogWindows:Error: UE4Editor-KismetCompiler.dll!FKismet2CompilerModule::CompileBlueprint() [d:\gh\gh4.16\engine\source\editor\kismetcompiler\private\kismetcompilermodule.cpp:247] Cook: LogWindows:Error: UE4Editor-BlueprintNativeCodeGen.dll!FBlueprintNativeCodeGenUtils::GenerateCppCode() [d:\gh\gh4.16\engine\source\developer\blueprintnativecodegen\private\blueprintnativecodegenutils.cpp:382] Cook: LogWindows:Error: UE4Editor-BlueprintNativeCodeGen.dll!FBlueprintNativeCodeGenModule::GenerateSingleAsset() [d:\gh\gh4.16\engine\source\developer\blueprintnativecodegen\private\blueprintnativecodegenmodule.cpp:462] Cook: LogWindows:Error: UE4Editor-BlueprintNativeCodeGen.dll!FBlueprintNativeCodeGenModule::GenerateFullyConvertedClasses() [d:\gh\gh4.16\engine\source\developer\blueprintnativecodegen\private\blueprintnativecodegenmodule.cpp:364] Cook: LogWindows:Error: UE4Editor-UnrealEd.dll!UCookOnTheFlyServer::CookByTheBookFinished() [d:\gh\gh4.16\engine\source\editor\unrealed\private\cookontheflyserver.cpp:6213] Cook: LogWindows:Error: UE4Editor-UnrealEd.dll!UCookOnTheFlyServer::TickCookOnTheSide() [d:\gh\gh4.16\engine\source\editor\unrealed\private\cookontheflyserver.cpp:2202] Cook: LogWindows:Error: UE4Editor-UnrealEd.dll!UCookCommandlet::CookByTheBook() [d:\gh\gh4.16\engine\source\editor\unrealed\private\commandlets\cookcommandlet.cpp:895] Cook: LogWindows:Error: UE4Editor-UnrealEd.dll!UCookCommandlet::Main() [d:\gh\gh4.16\engine\source\editor\unrealed\private\commandlets\cookcommandlet.cpp:558] Cook: LogWindows:Error: UE4Editor-Cmd.exe!FEngineLoop::PreInit() [d:\gh\gh4.16\engine\source\runtime\launch\private\launchengineloop.cpp:2068] Cook: LogWindows:Error: UE4Editor-Cmd.exe!GuardedMain() [d:\gh\gh4.16\engine\source\runtime\launch\private\launch.cpp:127] Cook: LogWindows:Error: UE4Editor-Cmd.exe!GuardedMainWrapper() [d:\gh\gh4.16\engine\source\runtime\launch\private\windows\launchwindows.cpp:134] Cook: LogWindows:Error: UE4Editor-Cmd.exe!WinMain() [d:\gh\gh4.16\engine\source\runtime\launch\private\windows\launchwindows.cpp:210] Cook: LogWindows:Error: UE4Editor-Cmd.exe!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253] Cook: LogWindows:Error: kernel32.dll!0x00000000779459CD Cook: LogWindows:Error: ntdll.dll!0x0000000077A7A561 Cook: LogWindows:Error: ntdll.dll!0x0000000077A7A561 Cook: LogWindows:Error: Cook: LogWindows:Error: end: stack for UAT
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-44112 in the post.