system null reference in .net [duplicate]

Question

When i try to update a value in form its showing system null expression.

here is my code:

[HttpPost]
public ActionResult EditPage(PageMasterViewModels pageupdate,int id)
{

    var pagedata = _db.PageMaster.Where(x => x.PageId == id).FirstOrDefault();
    if (pagedata != null)
    {
        pagedata.PageName = pageupdate.PageName;
        pagedata.PageMetaTag = pageupdate.PageMetaTag;
        pagedata.PageTitle = pageupdate.PageTitle;
        pagedata.PageDescription = pageupdate.PageDescription;
        pagedata.PageMetaDescription = pageupdate.PageMetaDescription;
        pageupdate.UpdatedDate = DateTime.Now;

        _db.SaveChanges();

    }
    return Redirect("PageDetails");


}

Error:

Answer 1

Your pageData's property PageName is Null.If you want to solve this problem you can edit data in your db or change PageData entity to

class PageData{
    public string? PageName {get;set;}
}