Errors in Emscripten when building to WebGL

I have managed to build several WebGL applications but for a more complex project I'm getting the following errors:

Failed to run "C:\Program Files\Unity 5.0.0b9\Editor\Data\PlaybackEngines\webglsupport/BuildTools/Emscripten_Win/python/2.7.5.3_64bit/python.exe"

Program: "C:\Program Files\Unity 5.0.0b9\Editor\Data\PlaybackEngines\webglsupport/BuildTools/Emscripten_Win/python/2.7.5.3_64bit/python.exe" Args: "C:\Program Files\Unity 5.0.0b9\Editor\Data\PlaybackEngines\webglsupport/BuildTools/Emscripten/emcc" -Oz -std=c++11 -Wno-unused-value -Wno-invalid-offsetof -I-I"J:/Programming/Production/ElfaWebPlanner/Assets/../Temp/StagingArea/Data\Libraries\bdwgc/include" -I"J:/Programming/Production/ElfaWebPlanner/Assets/../Temp/StagingArea/Data\Libraries\libil2cpp/include" -I"J:/Programming/Production/ElfaWebPlanner/Assets/../Temp/StagingArea/Data\il2cppOutput" -nostdinc -c @"C:\Users\sewi\AppData\Local\Temp\tmp3bd327a2.tmp"

WARNING: sanity check failed to run [Errno 13] Permission denied: 'C:\Program Files\Unity 5.0.0b9\Editor\Data\PlaybackEngines\webglsupport/BuildTools/emscripten.config_sanity'WARNING root: did not see a source tree above the LLVM root directory (guessing based on directory of C:\Program Files\Unity 5.0.0b9\Editor\Data\PlaybackEngines\webglsupport/BuildTools/Emscripten_FastComp_Win\llc), could not verify version numbers match
INFO root: (Emscripten: Running sanity checks)
WARNING root: java does not seem to exist, required for closure compiler, which is optional (define JAVA in ~/.emscripten if you want it)
WARNING root: -I or -L of an absolute path "-IJ:/Programming/Production/ElfaWebPlanner/Assets/../Temp/StagingArea/Data\Libraries\libil2cpp/include" encountered. If this is to a local system header/library, it may cause problems (local system files make sense for compiling natively on your system, but not necessarily to JavaScript). Pass '-Wno-warn-absolute-paths' to emcc to hide this warning.
In file included from J:/Programming/Production/ElfaWebPlanner/Assets/../Temp/StagingArea/Data\il2cppOutput\Bulk_Arrays_0.cpp:15:
J:/Programming/Production/ElfaWebPlanner/Assets/../Temp/StagingArea/Data\Libraries\libil2cpp/include\codegen/il2cpp-codegen.h:156:1: warning: function declared 'noreturn' should not return [-Winvalid-noreturn]
}

This code is protected code beloning to a client so I can't submit it to the bugtracker. I am however eager to do whatever other tests necessary to solve this problem.

The Permission denied could point to an issue with the filesystem, but equally this could be a codegeneration issue. Please PM me so we can work out how to get a repro project.

I got this error too, I had to set the python.exe to run as administrator to get it to work...

Ill go ahead and try the administrator-thing first, if that doesn't work I'll contact you RalphH. No point disturbing you if it works well in admin mode!

Mine's throwing the same error. If you guys get it to work, some instructions on how to fix would be awesome

Either way, we'd like a bug report, so we can avoid people from hitting this (while getting all the information for us to diagnose what is up).

How do I pm? Couldn't find it. Is it the "start conversation" thing?

I believe that “start conversation” just starts a new thread, so you probably don’t want that. You can DM Ralph on Twitter (link is in his signature) or email me: joshuap at unity3d.com and we can get the details. Thanks.

Ralph messaged me, so thats sorted, but thanks!

And for everyone’s knowledge, In my case the error was, and I’m citing RalphH here:
“The issue is that ‘PluginX.dll’ [name redacted] is obfuscating all names with non utf8 characters. That’s something we haven’t support, but is known.”

It's ok to mention the plugin name really, especially as I think other will be helped by knowing while we work on a fix; Daikon Forge Gui is shipped as an obfuscated .dll, the type/method names are all severly mangled; I've got it to compile earlier, however, I need to verify the fix for the runtime.

Ok absolutely, you are right.

Seeing that Daikon Forge is also available (was atleast) with sources in addition to the dll, would that fix the problem with mangled names?

Yes. Ofcourse, we will ship a build which fixes this.