Build Configuration

In addition to being added to the generated UE4 project under the Config/UnrealBuildTool folder, UnrealBuildTool reads settings from XML config files in the following locations:

  • Engine/Saved/UnrealBuildTool/BuildConfiguration.xml
  • User Folder/AppData/Roaming/Unreal Engine/UnrealBuildTool/BuildConfiguration.xml
  • My Documents/Unreal Engine/UnrealBuildTool/BuildConfiguration.xml

Keep reading to learn more about the following properties, which help to set and customize build configuration(s).

XboxOnePlatform

Compiler
Version of the compiler toolchain to use on Windows platform. A value of "default" will be changed to a specific version at UBT startup.
bOverrideUseFastPDBLinking
Override for fast PDB linking on Xbox - seems a bit more stable on Xbox One than on PC so it's good to set them separately.

BuildConfiguration

bGeneratedSYMFile
Whether to generate dSYM files Lists Architectures that you want to build.
bEnableAddressSanitizer
Enables address sanitizer (ASan).
bEnableThreadSanitizer
Enables thread sanitizer (TSan).
bEnableUndefinedBehaviorSanitizer
Enables undefined behavior sanitizer (UBSan).
BaseLogFileName
Specifies the file to use for logging
bAllowDistccLocalFallback
When enabled allows DMUCS/Distcc to fallback to local compilation when remote compiling fails. Defaults to true as separation of pre-process and compile stages can introduce non-fatal errors.
bVerboseDistccOutput
When true enable verbose distcc output to aid debugging.
DistccExecutablesPath
Path to the Distcc and DMUCS executables.
DMUCSCoordinator
DMUCS coordinator hostname or IP address.
DMUCSDistProp
The DMUCS distinguishing property value to request for compile hosts.
bXGENoWatchdogThread
Whether to use the no_watchdog_thread option to prevent VS2015 toolchain stalls.
bShowXGEMonitor
Whether to display the XGE build monitor.
bStopXGECompilationAfterErrors
When enabled, XGE will stop compiling targets after a compile error occurs. Recommended, as it saves computing resources for others.
bWriteSolutionOptionFile
Whether to write a solution option (suo) file for the sln.
bAddFastPDBToProjects
Whether to add the -FastPDB option to build command lines by default.
bUsePerFileIntellisense
Whether to generate per-file intellisense data.
bEditorDependsOnShaderCompileWorker
Whether to include a dependency on ShaderCompileWorker when generating project files for the editor.
bDebugBuildsActuallyUseDebugCRT
Enables the debug C++ runtime (CRT) for debug builds. By default we always use the release runtime, since the debug version isn't particularly useful when debugging Unreal Engine projects, and linking against the debug CRT libraries forces our third party library dependencies to also be compiled using the debug CRT (and often perform more slowly). Often it can be inconvenient to require a separate copy of the debug versions of third party static libraries simply so that you can debug your program's code.
bUseInlining
Enable inlining for all modules.
bUseXGEController
Whether the XGE controller worker and modules should be included in the engine build. These are required for distributed shader compilation using the XGE interception interface.
bUseUnityBuild
Whether to unify C++ code into larger files for faster compilation.
bForceUnityBuild
Whether to force C++ source files to be combined into larger files for faster compilation.
bUseAdaptiveUnityBuild
Uses a heuristic to determine which files are currently being iterated on, and excludes them from unity blobs, resulting in faster incremental compile times. The current implementation uses the read-only flag to distinguish the working set, assuming that files will be made writable by the source control system if they are being modified. This is true for Perforce, but not for Git.
bAdaptiveUnityDisablesOptimizations
Disables optimization for files that are in the adaptive non-unity working set.
bAdaptiveUnityDisablesPCH
Disables force-included PCHs for files that are in the adaptive non-unity working set.
bAdaptiveUnityCreatesDedicatedPCH
Creates a dedicated PCH for each source file in the working set, allowing faster iteration on cpp-only changes.
bAdaptiveUnityEnablesEditAndContinue
Creates a dedicated PCH for each source file in the working set, allowing faster iteration on cpp-only changes.
MinGameModuleSourceFilesForUnityBuild
The number of source files in a game module before unity build will be activated for that module. This allows small game modules to have faster iterative compile times for single files, at the expense of slower full rebuild times. This setting can be overridden by the bFasterWithoutUnity option in a module's Build.cs file.
bShadowVariableErrors
Forces shadow variable warnings to be treated as errors on platforms that support it.
bUndefinedIdentifierErrors
Forces the use of undefined identifiers in conditional expressions to be treated as errors.
bUseFastMonoCalls
New Monolithic Graphics drivers have optional "fast calls" replacing various D3d functions.
bUseFastSemanticsRenderContexts
New Xbox driver supports a "fast semantics" context type. This switches it on for the immediate and deferred contexts Try disabling this if you see rendering issues and/or crashes inthe Xbox RHI.
NumIncludedBytesPerUnityCPP
An approximate number of bytes of C++ code to target for inclusion in a single unified C++ file.
bStressTestUnity
Whether to stress test the C++ unity build robustness by including all C++ files files in a project from a single unified file.
bDisableDebugInfo
Whether to globally disable debug info generation; see DebugInfoHeuristics.cs for per-config and per-platform options.
bDisableDebugInfoForGeneratedCode
Whether to disable debug info generation for generated files. This improves link times for modules that have a lot of generated glue code.
bOmitPCDebugInfoInDevelopment
Whether to disable debug info on PC in development builds (for faster developer iteration, as link times are extremely fast with debug info disabled).
bUsePDBFiles
Whether PDB files should be used for Visual C++ builds.
bUsePCHFiles
Whether PCH files should be used.
MinFilesUsingPrecompiledHeader
The minimum number of files that must use a pre-compiled header before it will be created and used.
bForcePrecompiledHeaderForGameModules
When enabled, a precompiled header is always generated for game modules, even if there are only a few source files in the module. This greatly improves compile times for iterative changes on a few files in the project, at the expense of slower full rebuild times for small game projects. This can be overridden by setting MinFilesUsingPrecompiledHeaderOverride in a module's Build.cs file.
bUseIncrementalLinking
Whether to use incremental linking or not. Incremental linking can yield faster iteration times when making small changes. Currently disabled by default because it tends to behave a bit buggy on some computers (PDB-related compile errors).
bAllowLTCG
Whether to allow the use of link time code generation (LTCG).
bPGOProfile
Whether to enable Profile Guided Optimization (PGO) instrumentation in this build.
bPGOOptimize
Whether to optimize this build with Profile Guided Optimization (PGO).
bAllowASLRInShipping
Whether to allow the use of ASLR (address space layout randomization) if supported. Only applies to shipping builds.
bSupportEditAndContinue
Whether to support edit and continue. Only works on Microsoft compilers.
bOmitFramePointers
Whether to omit frame pointers or not. Disabling is useful for e.g. memory profiling on the PC.
bUseMallocProfiler
If true, then enable memory profiling in the build (defines USE_MALLOC_PROFILER=1 and forces bOmitFramePointers=false).
bUseSharedPCHs
Enables "Shared PCHs", a feature which significantly speeds up compile times by attempting to share certain PCH files between modules that UBT detects is including those PCH's header files.
bUseShippingPhysXLibraries
True if Development and Release builds should use the release configuration of PhysX/APEX.
bUseCheckedPhysXLibraries
True if Development and Release builds should use the checked configuration of PhysX/APEX. if bUseShippingPhysXLibraries is true this is ignored.
bCheckLicenseViolations
Tells the UBT to check if module currently being built is violating EULA.
bBreakBuildOnLicenseViolation
Tells the UBT to break build if module currently being built is violating EULA.
bUseFastPDBLinking
Whether to use the :FASTLINK option when building with /DEBUG to create local PDBs on Windows. Fast, but currently seems to have problems finding symbols in the debugger.
bCreateMapFile
Outputs a map file as part of the build.
bCheckSystemHeadersForModification
Whether headers in system paths should be checked for modification when determining outdated actions.
bFlushBuildDirOnRemoteMac
Whether to clean Builds directory on a remote Mac before building.
bPrintToolChainTimingInfo
Whether to write detailed timing info from the compiler and linker.
CppStandard
Which C++ standard to use for compiling this target
bStripSymbols
Whether to strip iOS symbols or not (implied by bGeneratedSYMFile).
bIgnoreOutdatedImportLibraries
Whether to ignore import library files that are out of date when building targets. Set this to true to improve iteration time. By default we don't bother relinking targets if only a dependent .lib has changed, as chances are that the import library wasn't actually different unless a dependent header file of this target was also changed, in which case the target would be rebuilt automatically.
bPrintDebugInfo
Whether debug info should be written to the console.
bLogDetailedActionStats
Whether to log detailed action stats. This forces local execution.
bAllowHybridExecutor
Whether the hybrid executor will be used (a remote executor and local executor).
bAllowXGE
Whether XGE may be used.
bAllowSNDBS
Whether SN-DBS may be used.
bUseUBTMakefiles
Enables support for very fast iterative builds by caching target data. Turning this on causes Unreal Build Tool to emit 'UBT Makefiles' for targets when they're built the first time. Subsequent builds will load these Makefiles and begin outdatedness checking and build invocation very quickly. The caveat is that if source files are added or removed to the project, UBT will need to gather information about those in order for your build to complete successfully. Currently, you must run the project file generator after adding/removing source files to tell UBT to re-gather this information.
  • Adding/removing .cpp files
  • Adding/removing .h files with UObjects
  • Adding new UObject types to a file that didn't previously have any
  • Changing global build settings (most settings in this file qualify.)
  • Changed code that affects how Unreal Header Tool works
This also enables the fast include file dependency scanning and caching system that allows Unreal Build Tool to detect out of date dependencies very quickly. When enabled, a deep C++ include graph does not have to be generated, and instead we only scan and cache indirect includes for after a dependent build product was already found to be out of date. During the next build, we'll load those cached indirect includes and check for any that are outdated.
bAllowDistcc
Whether DMUCS/Distcc may be used. Distcc requires some setup - so by default disable it so we don't break local or remote building.
bAllowParallelExecutor
Whether to allow using parallel executor on Windows.

HybridExecutor

MaxLocalActions
Maximum number of actions to execute locally

BuildMode

bIgnoreJunk
Whether to skip checking for files identified by the junk manifest

ProjectFileGenerator

DisablePlatformProjectGenerators
Platforms to disable native project file generators for. Platforms with native project file generators typically require IDE extensions to be installed.
Format
Default list of project file formats to generate
bIncludeDocumentation
True if we should include documentation in the generated projects
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac)
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in

LocalExecutor

ProcessorCountMultiplier
Processor count multiplier for local execution. Can be below 1 to reserve CPU for other tasks. When using the local executor (not XGE), run a single action on each CPU core. Note that you can set this to a larger value to get slightly faster build times in many cases, but your computer's responsiveness during compiling may be much worse.
MaxProcessorCount
Maximum processor count for local execution.

ParallelExecutor

ProcessorCountMultiplier
Processor count multiplier for local execution. Can be below 1 to reserve CPU for other tasks.
MaxProcessorCount
Maximum processor count for local execution.
bStopCompilationAfterErrors
When enabled, will stop compiling targets after a compile error occurs.

SNDBS

ProcessorCountMultiplier
Processor count multiplier for local execution. Can be below 1 to reserve CPU for other tasks.
MaxProcessorCount
Maximum processor count for local execution.

CLionGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

CMakefileGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

CodeLiteGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

EddieProjectFileGenerator

bIncludeDocumentation

True if we should include documentation in the generated projects.

bMasterProjectNameFromFolder

If true, sets the master project name according to the name of the folder it's in.

MasterProjectName

Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

KDevelopGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

MakefileGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

QMakefileGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

VSCodeProjectFileGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

VCProjectFileGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).
Version
The version of Visual Studio to generate project files for.

XcodeProjectFileGenerator

bIncludeDocumentation
True if we should include documentation in the generated projects.
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in.
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac).

SourceFileWorkingSet

GitPath
Sets the path to use for the Git executable. Defaults to "git" (assuming it's in the PATH).
Provider
Sets the provider to use for determining the working set.
RepositoryPath
Sets the path to use for the repository. Interpreted relative to the UE root directory (ie. folder above the Engine folder) if relative.

VCMacProjectFileGenerator

Version
The version of Visual Studio to generate project files for.
bIncludeDocumentation
True if we should include documentation in the generated projects
MasterProjectName
Name of the master project file (e.g. base file name for the solution file for Visual Studio, or the Xcode project file on Mac)
bMasterProjectNameFromFolder
If true, sets the master project name according to the name of the folder it's in

IOSToolChain

BuildIOSVersion
Which version of the iOS to allow at build time.
bUseDangerouslyFastMode
If this is set, then we don't do any post-compile steps except moving the executable into the proper spot on the Mac.
IOSSDKVersion
Which version of the iOS SDK to target at build time.

RemoteMac

ServerName
These two variables will be loaded from XML config file in XmlConfigLoader.Init()
UserName
The remote username
SshPrivateKey
Instead of looking for RemoteToolChainPrivate.key in the usual places (Documents/Unreal Engine/UnrealBuildTool/SSHKeys, Engine/Build/SSHKeys), this private key will be used if set
RsyncAuthentication
The authentication used for Rsync (for the -e rsync flag)
SshAuthentication
The authentication used for SSH (probably similar to RsyncAuthentication)

HTML5Platform

HTML5Architecture

Architecture to build for.

UEBuildConfiguration

bAllowHotReloadFromIDE
True if hot-reload from IDE is allowed.
bDoNotBuildUHT
If true, do not build UHT, assume it is already built.
bFailIfGeneratedCodeChanges
If true, fail if any of the generated header files is out of date.
bForceDebugUnrealHeaderTool
If true, the Debug version of UnrealHeaderTool will be build and run instead of the Development version.
bForceHeaderGeneration
If true, force header regeneration. Intended for the build machine.

WindowsPlatform

bStrictConformanceMode
Enables strict standard conformance mode (/permissive-) in VS2017+.
Compiler
Version of the compiler toolchain to use on Windows platform. A value of "default" will be changed to a specific version at UBT startup.
CompilerVersion
The specific toolchain version to use. This may be a specific version number (such as "14.13.26128") or the string "Latest" to select the newest available version. By default, we use the toolchain version indicated by WindowsPlatform.DefaultToolChainVersion if it is available, or the latest version otherwise.
StaticAnalyzer
The static analyzer to use.
WindowsSdkVersion
The specific Windows SDK version to use. This may be a specific version number (such as "8.1", "10.0", or "10.0.10150.0") or the string "Latest" to select the newest available version. By default, we use the Windows SDK version indicated by WindowsPlatform.DefaultWindowsSdkVersion if it is available, or the latest version otherwise.
PCHMemoryAllocationFactor
Determines the amount of memory that the compiler allocates to construct precompiled headers (/Zm).
bClangTimeTrace
(Experimental) Appends the -ftime-trace argument to the command line for Clang, to output a JSON file containing a timeline for the compile. See http://aras-p.info/blog/2019/01/16/time-trace-timeline-flame-chart-profiler-for-Clang for more info.

WindowsTargetRules

ObjSrcMapFile
Whether we should export a file containing .obj->source file mappings.