WebGL development build error

version 2019.3.0a5

I can build my project normally but not in development mode

Failed running C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp/build/il2cpp.exe --convert-to-cpp --emit-null-checks --enable-stacktrace --enable-array-bounds-check --dotnetprofile="unityaot" --compile-cpp --libil2cpp-static --platform="WebGL" --architecture="EmscriptenJavaScript" --configuration="Release" --outputpath="MYPATH\Assets /../Temp/StagingArea/Data\Native\build.bc" --cachedirectory="MYPATH\Assets\..\Library/il2cpp_cache" --compiler-flags="-Oz" --emit-method-map --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_AccessibilityModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_AIModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_AndroidJNIModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_AnimationModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_ARModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_AssetBundleModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_AudioModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_ClothModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_CoreModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_CrashReportingModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_DirectorModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_DSPGraphModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_GameCenterModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_GridModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_HotReloadModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_ImageConversionModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_IMGUIModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_InputLegacyModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_InputModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_JSONSerializeModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_LocalizationModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_ParticleSystemModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_PerformanceReportingModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_Physics2DModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_PhysicsModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_ProfilerModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_ScreenCaptureModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_SharedInternalsModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_SpriteMaskModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_SpriteShapeModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_StreamingModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_SubstanceModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_TerrainModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_TerrainPhysicsModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_TextCoreModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_TextRenderingModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_TilemapModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_TLSModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UIElementsModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UIModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UmbraModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UNETModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityAnalyticsModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityConnectModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityTestProtocolModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityWebRequestAssetBundleModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityWebRequestAudioModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityWebRequestModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityWebRequestTextureModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_UnityWebRequestWWWModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_VehiclesModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_VFXModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_VideoModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_VRModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_WebGLModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_WindModule_Dynamic.bc" --additional-libraries="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/PlaybackEngines/WebGLSupport\BuildTools\lib\modules_development\WebGLSupport_XRModule_Dynamic.bc" --enable-debugger --profiler-report --map-file-parser="C:/Program Files/Unity/Hub/Editor/2019.3.0a5/Editor/Data/Tools/MapFileParser/MapFileParser.exe" --directory="C:/Users/giuseppei/OneDrive - Agic Technology srl/Documenti/Unity/MyGPViewer4.0/Temp/StagingArea/Data/Managed" --generatedcppdir="C:/Users/giuseppei/OneDrive - Agic Technology srl/Documenti/Unity/MyGPViewer4.0/Temp/StagingArea/Data/il2cppOutput"

stdout:
Building build.bc with EmscriptenToolChain
Output directory: MYPATH\Temp\StagingArea\Data\Native
Cache directory: MYPATH\Library\il2cpp_cache
il2cpp.exe didn't catch exception: Unity.IL2CPP.Building.BuilderFailedException: In file included from MYPATH\Temp\StagingArea\Data\il2cppOutput\lumpedcpp\Lump_libil2cpp_os.cpp:7:
MYPATH\Temp\StagingArea\Data\il2cppOutput\lumpedcpp/..\..\..\..\..\..\..\..\..\..\..\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\libil2cpp\os\Emscripten\SocketBridge.cpp:8:10: fatal error: 'emscripten/posix_socket.h' file not found
#include <emscripten/posix_socket.h>
^~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
ERROR:root:compiler frontend failed to generate LLVM bitcode, halting

Invocation was: Executable: "C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten_Win\python\2.7.5.3_64bit\python.exe"
Arguments: -E "C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\em++" -Wno-unused-value -Wno-invalid-offsetof -nostdinc -fno-strict-overflow -Wno-null-conversion -std=c++11 -s USE_PTHREADS=1 -O3 -Oz -DNET_4_0 -DUNITY_AOT -DIL2CPP_MONO_DEBUGGER=1 -DIL2CPP_DEBUGGER_PORT=56000 -DPLATFORM_UNITY -DUNITY_USE_PLATFORM_STUBS -DENABLE_OVERRIDABLE_ALLOCATORS -DIL2CPP_ON_MONO=1 -DDISABLE_JIT=1 -DDISABLE_REMOTING=1 -DHAVE_CONFIG_H -DMONO_DLL_EXPORT=1 -DGC_NOT_DLL -DRUNTIME_IL2CPP -DNDEBUG -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\libil2cpp" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\libil2cpp" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\bdwgc\include" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\xxHash" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\mono" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\mono\mono\eglib" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\mono\mono" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\mono\mono\sgen" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\mono\mono\utils" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\mono\mono\metadata" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\external\mono\mono\metadata\private" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\libil2cpp\os\c-api" -I"C:\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\libmono\config" "MYPATH\Temp\StagingArea\Data\il2cppOutput\lumpedcpp\Lump_libil2cpp_os.cpp" -o "MYPATH\Library\il2cpp_cache\libil2cpp\B9B59419A7EA6753C312FB9A0E581DC3.o"

in Unity.IL2CPP.Building.CppProgramBuilder.BuildAllCppFiles(IEnumerable`1 sourceFilesToCompile, IBuildStatisticsCollector statisticsCollector)
in Unity.IL2CPP.Building.CppProgramBuilder.Build(IBuildStatistics& statistics)
in il2cpp.Program.DoRun(String[] args)
in il2cpp.Program.Run(String[] args)
in il2cpp.Program.Main(String[] args)
stderr:

Eccezione non gestita: Unity.IL2CPP.Building.BuilderFailedException: In file included from MYPATH\Temp\StagingArea\Data\il2cppOutput\lumpedcpp\Lump_libil2cpp_os.cpp:7:
MYPATH\Temp\StagingArea\Data\il2cppOutput\lumpedcpp/..\..\..\..\..\..\..\..\..\..\..\Program Files\Unity\Hub\Editor\2019.3.0a5\Editor\Data\il2cpp\libil2cpp\os\Emscripten\SocketBridge.cpp:8:10: fatal error: 'emscripten/posix_socket.h' file not found
#include <emscripten/posix_socket.h>
^~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
ERROR:root:compiler frontend failed to generate LLVM bitcode, halting

Hello, I had the same problem today (fatal error: ‘emscripten/posix_socket.h’ file not found), Unity 2019.2.0f. It helped me to clear Library and temp folder of the project, start unity and build again. the build succeed

Check your code Usually the problem is purely in the program code.
but there may also be problems due to the use of third-party plug-ins. Also check to see if the game uses an internet connection to write files, browsers don’t like when games download something.

I also recommend do not update project (you can have problems with) UnityEditor.BuildPlayerWindow + BuildMethodException

@trumanita I have the very same problem:

…\UNITY\Editors\2019.3.0a2\Editor\Data\il2cpp\libil2cpp\os\Emscripten\SocketBridge.cpp:8:10: fatal error: ‘emscripten/posix_socket.h’ file not found

To be sure I checked that there really is no ‘posix_socket.h’ in the unity install path.

This only happens when I attempt a development build. For deployment the build is successful.

Same with 2019.2.16f