Error packaging project to HTML5 with Emscipten

I’m getting these errors when packaging project to HTML 5. I’m using Emscipten 1.37.1

Try updating to newer Emscripten version. For example the complained -s WEBGL2_BACKWARDS_COMPATIBILITY_EMULATION=1 flag which UE 4.16 needs was introduced to Emscripten in version 1.37.3, which was dated 2/16/2017. (Emscripten 1.37.1 is from 12/26/2016).

I believe UE4.16 has some locally needed changes that are in the process of getting upstreamed, so Emscripten incoming might have some rough edges. For best compatibility, try using the Emscripten version that UE4.16 ships with.