Any idea about this exception

EXCEPTION :
The file '/Ueditor/net/controller.ashx' does not exist.
Full Stack Trace :
System.Web.HttpException (0x80004005): The file '/Ueditor/net/controller.ashx' does not exist. at

System.Web.UI.Util.CheckVirtualFileExists(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) at System.Web.Compilation.BuildManager.GetVPathBuildResult(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean ensureIsUpToDate) at System.Web.UI.SimpleHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) at System.Web.UI.SimpleHandlerFactory.GetHandler(HttpContext context, String requestType, String virtualPath, String path) at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)