WebGL Build Error

Hi When I Build UFE to WebGL , Error occurs.

Error log is following ↓

・Failed running F:\Unity2018_1_0f2\Editor\Data\il2cpp/build/il2cpp.exe --convert-to-cpp --compile-cpp --libil2cpp-static --platform="WebGL" --architecture="EmscriptenJavaScript" --configuration="Release" --outputpath="C:\Users\G015C1119\Documents\TestTTF2\Assets /../Temp/StagingArea/Data\Native\build.bc" --cachedirectory="C:\Users\G015C1119\Documents\TestTTF2\Assets\..\Library/il2cpp_cache" --compiler-flags="-Oz -DIL2CPP_EXCEPTION_DISABLED=1 " --emit-method-map --additional-libraries="F:\Unity2018_1_0f2\Editor\Data\PlaybackEngines\WebGLSupport\BuildTools\lib\modules\WebGLSupport_AccessibilityModule_Dynamic.bc"

・Exception: F:\Unity2018_1_0f2\Editor\Data\il2cpp/build/il2cpp.exe did not run properly!

・Build completed with a result of 'Failed'
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

・UnityEditor.BuildPlayerWindow+BuildMethodException: 5 errors
  at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) [0x0021f] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:182
  at UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) [0x00065] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:89
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

・IL2CPP error for method 'System.Int32 UnityEngine.NetworkPlayer::get_port()' in assembly 'C:\Users\G015C1119\Documents\TestTTF2\Temp\StagingArea\Data\Managed\mscorlib.dll'
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・Error building Player: 4 errors

Error seems to occur in IL2CPP compiling.   What should I do?

Please comment.