შეცდომაა

System.ArgumentException: Value cannot be null or empty. Parameter name: contentType at System.Web.Mvc.FileResult..ctor(String contentType) at System.Web.Mvc.FileContentResult..ctor(Byte[] fileContents, String contentType) at System.Web.Mvc.Controller.File(Byte[] fileContents, String contentType, String fileDownloadName) at EiecSiteUser.Controllers.ServicesController.GetCoursePhoto(Int32 courseId, String who) in D:\Projects\Projects 2022\EiecSiteUser\EiecSiteUser\Controllers\ServicesController.cs:line 70