Error: 'System.Web.WebPages.Html.HtmlHelper' does not contain a definition for 'Action' and no extension method 'Action' accepting a first argument of type 'System.Web.WebPages.Html.HtmlHelper' could be found (are you missing a using directive or an assembly reference?)

E:\Users\jon\Documents\Visual Studio 2017\Projects\NG-Metering\NG-Metering.Web\AppData\04cc204f-79c2-40f9-8fde-27abbb0ad5b8\NGMacroPartialSliderGridTimeline.cshtml

Okay, I’m confused again … would anyone be able to tell me how to clean out an old item in my App_Data folder that is not referenced in either the umbraco.config, nor the package.config, nor any actual file when doing a solution-wide search?

The issue is this same directory, and the corresponding *.cshtml file are causing the build to fail and I’ve tried to clean & rebuild, restarting VS, and was about to remove the .suo file but I thought I would ask here before I made some idiot mistake!

PS. I also tried deleting the umbraco.config and the preview and temp folders in the App_Data folder too?

PPS. the “outdated” file is throwing this error, however, the latest version, and all others like it, are not?

Any and all help would be greatly appreciated as I can't get my solution to build until I resolve this!

Cheers!