Custom WebGLTemplate not found?

Copied Default WebGL template from C:\Program Files\Unity\Editor\Data\PlaybackEngines\webglsupport\BuildTools\WebGLTemplates\Default to Assets\WebGLTemplates\Foobar

Exception: Invalid WebGL template path: C:\Program Files\Unity\Editor\Data\PlaybackEngines\webglsupport/BuildTools\WebGLTemplates\Foobar! Select a template in player settings.
UnityEditor.WebGL.WebGlBuildPostprocessor.GetTemplateFolder ()
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.BuildPlayerWindow:BuildPlayerAndRun()

Running Unity 5.0.1f1 on Windows.

Hi, this is a bug. You can follow its progress under Unity Issue Tracker - Windows: Failure to build with custom WebGL Template

As a workaround you can make a custom build script and copy the template yourself at the end of the build process.