Static JavaScript and CSS files giving a 500 error

I created an MVC widget that needs some external CSS and JavaScript files. I created a new folder on the file system called 'MvcAssets', which is on the same level as Mvc.

 When I make a reference to any of the static files (.js or .css), I'm getting a 500 error.  All of the files in question were compiled/generated using pre-compilers/build tools (e.g. Gulp). I don't see any reason why this should cause a problem, but my main suspicion is that there's something about the file's "modified" timestamp that isn't meshing with Sitefinity.

 Has anyone encountered similar issues? Any suggestions for resolution?

Bump

BUMP

im case of u are ligged in the dashboard  by admin lofin - no error

for not logged - 500 error

[HttpException (0x80004005): Сбой выполнения Execute URL.] System.Web.Hosting.ISAPIWorkerRequestInProcForIIS6.BeginExecuteUrl(String url, String method, String childHeaders, Boolean sendHeaders, Boolean addUserIndo, IntPtr token, String name, String authType, Byte[] entity, AsyncCallback cb, Object state) +1687418 System.Web.HttpResponse.BeginExecuteUrlForEntireResponse(String pathOverride, NameValueCollection requestHeaders, AsyncCallback cb, Object state) +412 System.Web.DefaultHttpHandler.BeginProcessRequest(HttpContext context, AsyncCallback callback, Object state) +192 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +103 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155