I'm getting an error when trying to build any project in WebGL. I'm on 5.1.3p1 but the error also appears on 5.1.2f1. Building has worked for me before on 5.1.2, so it makes me think I inadvertently changed something on my system. I've also tried building an empty 3d project on 5.1.3p1, which gives me the same error. I've attached the log from this last attempt. I'm no expert at reading logs, but I did notice that the first error that shows up appears to be something to do with loading the python extension module _multiprocessing: File "C:\Python27\lib\multiprocessing\__init__.py", line 84, in <module> import _multiprocessing ImportError: DLL load failed: %1 is not a valid Win32 application. However, I have the _multiprocessing file at C:\Python27\DLLs\_multiprocessing.pyd and can import it just fine (I think) in IDLE.