Unity 5.3.4 WebGL crash (tons of errors) on build ?

When I build for windows it works fine but when I build for WebGL it crash always. (10 Errors)
I have reinstall Unity and start it as admin, nothing works.

Sorry for my english I'm belgian and speaking german

System:

Windows 10
Amd FX-8350
Nvidia GTX 980

Thanks

Spoiler: Error Message 1

Failed running "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" -Oz -std=c++11 -Wno-unused-value -Wno-invalid-offsetof -I-I"C:/Users/Name/Documents/Unity/tictactoe_webgl/Assets/../Temp/StagingArea/Data\Libraries\bdwgc/include" -I"C:/Users/Name/Documents/Unity/tictactoe_webgl/Assets/../Temp/StagingArea/Data\Libraries\libil2cpp/include" -I"C:/Users/Name/Documents/Unity/tictactoe_webgl/Assets/../Temp/StagingArea/Data\il2cppOutput" -nostdinc -c @"C:\Users\Name\AppData\Local\Temp\tmp391d3a7c.tmp"

Spoiler: Error Message 2

Exception: IL2CPP compile failed.
NativeCompiler.RunProgram (System.Diagnostics.ProcessStartInfo startInfo) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/NativeCompiler.cs:62)
NativeCompiler.Execute (System.String arguments, System.String compilerPath) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/NativeCompiler.cs:26)
UnityEditor.WebGL.Il2Cpp.EmscriptenCompiler.LinkObjects (IEnumerable`1 sources, System.String outfile) (at /Users/builduser/buildslave/unity/build/PlatformDependent/WebGL/Extensions/Unity.WebGL.extensions/Il2Cpp/EmscriptenCompiler.cs:57)
UnityEditor.WebGL.Il2Cpp.EmscriptenCompiler.MultiThreadedCompile (System.String outfile, IEnumerable`1 sources, IEnumerable`1 includePaths, Boolean exceptionSupport) (at /Users/builduser/buildslave/unity/build/PlatformDependent/WebGL/Extensions/Unity.WebGL.extensions/Il2Cpp/EmscriptenCompiler.cs:44)
UnityEditor.WebGL.Il2Cpp.EmscriptenCompiler.CompileDynamicLibrary (System.String outFile, IEnumerable`1 sources, IEnumerable`1 includePaths, IEnumerable`1 libraries, IEnumerable`1 libraryPaths) (at /Users/builduser/buildslave/unity/build/PlatformDependent/WebGL/Extensions/Unity.WebGL.extensions/Il2Cpp/EmscriptenCompiler.cs:21)
UnityEditorInternal.IL2CPPBuilder.Run () (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:218)
UnityEditorInternal.IL2CPPUtils.RunIl2Cpp (System.String stagingAreaData, IIl2CppPlatformProvider platformProvider, System.Action`1 modifyOutputBeforeCompile, UnityEditor.RuntimeClassRegistry runtimeClassRegistry, Boolean developmentBuild) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:135)
UnityEditor.WebGL.WebGlBuildPostprocessor.PostProcess (BuildPostProcessArgs args) (at /Users/builduser/buildslave/unity/build/PlatformDependent/WebGL/Extensions/Unity.WebGL.extensions/BuildPostprocessor.cs:301)
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) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:316)
UnityEditor.BuildPlayerWindow:BuildPlayerAndRun()

 

Thanks, My name is 'Mike' and how can I made a bug report with repro ?

 

Thank you

Case number:
780610

 

So I have done what had been advised in a support email but nothing has helped (all Paths are there, Python was installed (and I have tested when it is uninstallt)and I have created a new Profile) I don't know what the problem is.