This error can occur when adding the ReactJS.NET package to an ASP.Net project and deploying to AppHarbor:
error ASPCONFIG: Could not load file or assembly 'ClearScriptV8-32.DLL' or one of its dependencies. The specified module could not be found.
When you added this Nuget package, it adds the following four assemblies to your project:
ClearScriptV8-32.dll ClearScriptV8-64.dll v8-ia32.dll v8-x64.dll
To fix the error, you need to drag them to the root of the project, and set the “Copy to Output Directory” to “Do not copy”.
You’ll also need to set “Build Action” to “Content”, or the JSX files won’t be found when you deploy.