WebGL build FileNotFoundException

Hi, I'm trying to make a build of a very simple setup: just a model, the standard shader and a C# script that orbits the camera on touch. When building I get a FileNotFoundException. It seems the Builds.html.mem file is not created. Any ideas?

I'm running Unity3D v5.2.1f1 64bit in Administrator mode with Python 2.7

FileNotFoundException: Temp/StagingArea/Data\Builds.html.mem does not exist System.IO.File.Copy (System.String sourceFileName, System.String destFileName, Boolean overwrite) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System.IO/File.cs:107) UnityEditor.WebGL.WebGlBuildPostprocessor.CopyFileFromStagingAreaToInstallPath (BuildPostProcessArgs args, System.String file) UnityEditor.WebGL.WebGlBuildPostprocessor.CopyFilesFromStagingAreaToInstallPath (BuildPostProcessArgs args, IEnumerable`1 files) UnityEditor.WebGL.WebGlBuildPostprocessor.CopyFinalFilesToInstallPath (BuildPostProcessArgs args) UnityEditor.WebGL.WebGlBuildPostprocessor.PostProcess (BuildPostProcessArgs args) UnityEditor.PostprocessBuildPlayer.Postprocess (BuildTarget target, System.String installPath, System.String companyName, System.String productName, Int32 width, Int32 height, System.String downloadWebplayerUrl, System.String manualDownloadWebplayerUrl, BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:316) UnityEditor.HostView:OnGUI()