Unable to package for HTML5

I am trying to package my project for deploying on HTML5. However, I am unable to do so.
Here is the error I am getting

INFO:root:(Emscripten: Running sanity checks)
2>  INFO:root:Closure compiler (E:\UE4\Epic Games\4.12\Engine\Source\ThirdParty\HTML5\emsdk\emscripten\1.35.0\third_party\closure-compiler\compiler.jar) does not exist, check the paths in E:\UE4\Epic Games\4.12\Engine\Intermediate\Build\HTML5\.emscripten
2>  INFO:root:closure compiler will not be available
2>EXEC : error : Linking globals named '_Z14UELinkerFixupsv': symbol multiply defined!
2>  Traceback (most recent call last):
2>    File "E:\UE4\Epic Games\4.12\Engine\Source\ThirdParty\HTML5\emsdk\emscripten\1.35.0\emcc", line 1309, in <module>
2>      final = shared.Building.llvm_opt(final, link_opts, DEFAULT_FINAL)
2>    File "E:\UE4\Epic Games\4.12\Engine\Source\ThirdParty\HTML5\emsdk\emscripten\1.35.0\tools\shared.py", line 1465, in llvm_opt
2>      assert os.path.exists(target), 'Failed to run llvm optimizations: ' + output
2>  AssertionError: Failed to run llvm optimizations:
2>ERROR : UBT error : Failed to produce item: D:\GitLab\YoApp\YoApp\Binaries\HTML5\YoApp-HTML5-DebugGame.js
2>  Total build time: 155.46 seconds
2>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.MakeFile.Targets(42,5): error MSB3073: The command ""E:\UE4\Epic Games\4.12\Engine\Build\BatchFiles\Rebuild.bat" YoApp HTML5 DebugGame "D:\GitLab\YoApp\YoApp\YoApp.uproject" -waitmutex" exited with code -1.

I went to the path to look if the compiler.jar was present, I found out that it was not present. In fact the whole third_party folder under 1.35.0 was missing.

Can someone please guide me on how to proceed from here. Any help would be greatly appreciated.



You have installed on your computer Microsoft C++ Visual Studio 2015? If not, download it and install on your computer.

You always need Visual Studio when you create packages for any platform.

I have already installed that.

I have a similar error when I package C++ project, or if I enable “Nativize Blueprint Assets” in the project settings in the BP project.

HTML5 is still an experimental feature and sometimes it doesn’t work correctly.

I didn’t enable the “Nativize Blueprint Assets” but still its giving the error.