(Unity newbie) WebGL build errors, il2cpp and build.asm.js, build fails.

Hi, I've just started learning unity this week. my background is in 3d/maya etc. so I know relatively little when it comes to troubleshooting game engine stuff.

One of the courses I'm doing requires me to build a fairly simple scene for WebGL, however it is not building correctly, the build folder is empty, and i get the following 3 error messages (below). I tried reinstalling unity, and deleting the library/temp/project settings folders, neither have fixed it.

So i tried with an empty scene and i get the same error (as well as sometimes a different one about build.asm.js filenotfound) I have just tried installing unity on another computer and attempetd to build webgl there and it's not working either. Is it possible im doing something wrong in my installation, or missing a setting box.

Help is much appreciated, I'm at a loss, of what my next step is.

running 5.5.2p4 on Windows 10 64bit, I have uploaded the editor log as well.

Spoiler: Error Message 1

Failed running C:\Program Files\Unity\Editor\Data\il2cpp/build/il2cpp.exe --convert-to-cpp --compile-cpp --libil2cpp-static --platform="WebGL" --architecture="EmscriptenJavaScript" --configuration="Release" --outputpath="C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Assets /../Temp/StagingArea/Data\Native\build.js" --cachedirectory="C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Assets\..\Library/il2cpp_cache" --compiler-flags="-Oz -DIL2CPP_EXCEPTION_DISABLED=1 " --linker-flags="-s PRECISE_F32=2 -s DISABLE_EXCEPTION_CATCHING=0 --memory-init-file 1 -O3 -s NO_EXIT_RUNTIME=1 -g0 -s USE_WEBGL2=1 -s TOTAL_MEMORY=268435456 --separate-asm --emit-symbol-map --output_eol linux -s MEMFS_APPEND_TO_TYPED_ARRAYS=1 " --js-pre="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\prejs\FileSystem.js" --js-pre="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\prejs\MediaDevices.js" --js-pre="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\prejs\SendMessage.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Audio.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Cursor.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Eval.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\FileSystem.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\library_memfs.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Logging.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\SystemInfo.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\UnetWebSocket.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\WebCam.js" --js-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\WebRequest.js" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_AIModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_AnimationModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_AudioModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_ClothModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_CloudWebServicesModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_CoreModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_CrashReportingModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_IMGUIModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_JSONSerializeModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_ParticlesLegacyModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_ParticleSystemModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_Physics2DModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_PhysicsModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_TerrainModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_TerrainPhysicsModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_TextRenderingModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UIModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UmbraModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UNETModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityAdsModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityAnalyticsModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityConnectModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityWebRequestModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_VehiclesModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_VideoModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_VRModule_Dynamic.bc" --additional-libraries="C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_WebModule_Dynamic.bc" --map-file-parser="C:\Program Files\Unity\Editor\Data\Tools\MapFileParser\MapFileParser.exe" --extra-types.file="C:\Program Files\Unity\Editor\Data\il2cpp\il2cpp_default_extra_types.txt" --assembly="C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Temp\StagingArea\Data\Managed\Assembly-CSharp.dll" --assembly="C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Temp\StagingArea\Data\Managed\UnityEngine.dll" --generatedcppdir="C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Temp\StagingArea\Data\il2cppOutput"

stdout:
Building build.js with EmscriptenToolChain.
Output directory: C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Temp\StagingArea\Data\Native
Cache directory: C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Library\il2cpp_cache
ObjectFiles: 423 of which compiled: 54
Time Compile: 21528 milliseconds Bulk_mscorlib_1.cpp
Time Compile: 19508 milliseconds Bulk_mscorlib_6.cpp
Time Compile: 15954 milliseconds GenericMethods0.cpp
Time Compile: 15622 milliseconds Bulk_mscorlib_3.cpp
Time Compile: 13354 milliseconds Bulk_mscorlib_0.cpp
Time Compile: 13029 milliseconds Bulk_mscorlib_2.cpp
Time Compile: 12209 milliseconds Bulk_Mono.Security_0.cpp
Time Compile: 11589 milliseconds Bulk_System_0.cpp
Time Compile: 10777 milliseconds Bulk_mscorlib_5.cpp
Time Compile: 9113 milliseconds Bulk_Generics_0.cpp
Total compilation time: 46592 milliseconds.
Response file: C:\Users\Akhil\AppData\Local\Temp\_1089605905\response.rsp
Response file: C:\Users\Akhil\AppData\Local\Temp\_1785258754\response.rsp
il2cpp.exe didn't catch exception: Unity.IL2CPP.Building.BuilderFailedException: "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten_Win\python\2.7.5.3_64bit\python.exe" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\emcc" -o "C:\Users\Public\Documents\Unity Projects\SolarSystemSimulation\Library\il2cpp_cache\linkresult_4716BBDE61C052193BC90B64ABF049A2\build.js" -s PRECISE_F32=2 -s DISABLE_EXCEPTION_CATCHING=0 --memory-init-file 1 -O3 -s NO_EXIT_RUNTIME=1 -g0 -s USE_WEBGL2=1 -s TOTAL_MEMORY=268435456 --separate-asm --emit-symbol-map --output_eol linux -s MEMFS_APPEND_TO_TYPED_ARRAYS=1 --pre-js "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\prejs\FileSystem.js" --pre-js "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\prejs\MediaDevices.js" --pre-js "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\prejs\SendMessage.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Audio.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Cursor.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Eval.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\FileSystem.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\library_memfs.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\Logging.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\SystemInfo.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\UnetWebSocket.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\WebCam.js" --js-library "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\WebRequest.js" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_AIModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_AnimationModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_AudioModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_ClothModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_CloudWebServicesModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_CoreModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_CrashReportingModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_IMGUIModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_JSONSerializeModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_ParticlesLegacyModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_ParticleSystemModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_Physics2DModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_PhysicsModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_TerrainModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_TerrainPhysicsModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_TextRenderingModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UIModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UmbraModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UNETModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityAdsModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityAnalyticsModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityConnectModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_UnityWebRequestModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_VehiclesModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_VideoModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_VRModule_Dynamic.bc" "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_WebModule_Dynamic.bc" @"C:\Users\Akhil\AppData\Local\Temp\_1785258754\response.rsp"

WARNING:root:cannot check node version: invalid literal for int() with base 10: '22\r\n[0x7FFEC4A570E3] ANOMALY: use of REX'
WARNING:root:did not see a source tree above or next to the LLVM root directory (guessing based on directory of C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten_FastComp_Win\llc), could not verify version numbers match
INFO:rootEmscripten: Running sanity checks)
WARNING:root:java does not seem to exist, required for closure compiler, which is optional (define JAVA in C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\emscripten.config if you want it)
WARNING:root:closure compiler will not be available
WARNING:root:--separate-asm works best when compiling to HTML. otherwise, you must yourself load the '.asm.js' file that is emitted separately, and must do so before loading the main '.js` file
warning: unresolved symbol: glGetInternalformativ
warning: unresolved symbol: _ZN4FMOD13DSPConnection6setMixEf
warning: unresolved symbol: glUnmapBuffer
warning: unresolved symbol: glMapBufferRange
warning: unresolved symbol: glFlushMappedBufferRange
Traceback (most recent call last):
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\emcc", line 13, in <module>
emcc.run()
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\emcc.py", line 1510, in run
final = shared.Building.emscripten(final, append_ext=False, extra_args=extra_args)
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\tools\shared.py", line 1693, in emscripten
call_emscripten(cmdline)
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\emscripten.py", line 1753, in _main
temp_files.run_and_clean(lambda: main(
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\tools\tempfiles.py", line 78, in run_and_clean
return func()
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\emscripten.py", line 1758, in <lambda>
DEBUG=DEBUG,
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\emscripten.py", line 1659, in main
temp_files=temp_files, DEBUG=DEBUG)
File "C:\Program Files\Unity\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\Emscripten\emscripten.py", line 93, in emscript
post, funcs_js, need_asyncify, provide_fround, asm_safe_heap, sending, receiving, asm_setup, the_global, asm_global_vars, asm_global_funcs, pre_tables, final_function_tables, exports, last_forwarded_json = function_tables_and_exports(funcs, metadata, mem_init, glue, forwarded_data, settings, outfile, DEBUG)
File "C:\Program Files\Unity\Editor\Data\Playba<message truncated>

Spoiler: Error Message 2

Exception: C:\Program Files\Unity\Editor\Data\il2cpp/build/il2cpp.exe did not run properly!
UnityEditorInternal.Runner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, System.Action`1 setupStartInfo) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildUtils.cs:98)
UnityEditorInternal.IL2CPPBuilder.RunIl2CppWithArguments (System.Collections.Generic.List`1 arguments, System.Action`1 setupStartInfo, System.String workingDirectory) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:298)
UnityEditorInternal.IL2CPPBuilder.ConvertPlayerDlltoCpp (ICollection`1 userAssemblies, System.String outputDirectory, System.String workingDirectory) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:289)
UnityEditorInternal.IL2CPPBuilder.Run () (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:131)
UnityEditorInternal.IL2CPPUtils.RunIl2Cpp (System.String stagingAreaData, IIl2CppPlatformProvider platformProvider, System.Action`1 modifyOutputBeforeCompile, UnityEditor.RuntimeClassRegistry runtimeClassRegistry, Boolean debugBuild) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:39)
UnityEditor.WebGL.WebGlBuildPostprocessor.PostProcess (BuildPostProcessArgs args) (at /Users/builduser/buildslave/unity/build/PlatformDependent/WebGL/Extensions/Unity.WebGL.extensions/BuildPostprocessor.cs:560)
UnityEditor.PostprocessBuildPlayer.Postprocess (BuildTarget target, System.String installPath, System.String companyName, System.String productName, Int32 width, Int32 height, System.String downloadWebplayerUrl, System.String manualDownloadWebplayerUrl, BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.BuildReporting.BuildReport report) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:186)
UnityEditor.HostView:OnGUI()

Spoiler: Error Message 3

Exception: C:\Program Files\Unity\Editor\Data\il2cpp/build/il2cpp.exe did not run properly!
UnityEditorInternal.Runner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser, System.Action`1 setupStartInfo) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildUtils.cs:98)
UnityEditorInternal.IL2CPPBuilder.RunIl2CppWithArguments (System.Collections.Generic.List`1 arguments, System.Action`1 setupStartInfo, System.String workingDirectory) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:298)
UnityEditorInternal.IL2CPPBuilder.ConvertPlayerDlltoCpp (ICollection`1 userAssemblies, System.String outputDirectory, System.String workingDirectory) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:289)
UnityEditorInternal.IL2CPPBuilder.Run () (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:131)
UnityEditorInternal.IL2CPPUtils.RunIl2Cpp (System.String stagingAreaData, IIl2CppPlatformProvider platformProvider, System.Action`1 modifyOutputBeforeCompile, UnityEditor.RuntimeClassRegistry runtimeClassRegistry, Boolean debugBuild) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:39)
UnityEditor.WebGL.WebGlBuildPostprocessor.PostProcess (BuildPostProcessArgs args) (at /Users/builduser/buildslave/unity/build/PlatformDependent/WebGL/Extensions/Unity.WebGL.extensions/BuildPostprocessor.cs:560)
UnityEditor.PostprocessBuildPlayer.Postprocess (BuildTarget target, System.String installPath, System.String companyName, System.String productName, Int32 width, Int32 height, System.String downloadWebplayerUrl, System.String manualDownloadWebplayerUrl, BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.BuildReporting.BuildReport report) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:186)
UnityEditor.HostView:OnGUI()

 

Managed to get it to start building, by moving the project folder to C:\ root directory, and outputting the builds to a folder on C:\ as well.

Solution was in this thread

https://forum.unity3d.com/threads/e...xception-failed-building-webgl-player.332541/

 

Hello, I've just recreated and sent 3 bug reports (sorry if overkill) of the various il2cpp and build.asm.js errors. Hopefully they help.

Having the projects on C:\\ seems to be a stable fix and as soon as i try to build stuff from a project folder in My documents folder the WebGL builds fail. It worked on both computers. I was also able to go back and recreate the error on both computers, for the same project and an empty test project.

Good luck!