“值不能为空或空 . 当ModelState出错时，返回时最意外的行上的参数名称：contentPath“

我已经连续两个小时跟这个怪物讨价还价了 .

我收到此错误：

值不能为null或为空 . 参数名称：contentPath

在我看来这一行：

@Html.ValidationMessageFor(model => model.IssueName, 
  "", new { @class = "text-danger" })

下面给出的堆栈跟踪似乎表明已经对 Url.Content 进行了调用，但我没有进行此类调用 . 下面是堆栈跟踪，然后是该行周围的一些代码行导致错误：

[ArgumentException：Value不能为null或为空 . 参数名称：contentPath] System.Web.Mvc.UrlHelper.GenerateContentUrl（String contentPath，HttpContextBase httpContext）125 System.Web.Mvc.UrlHelper.Content（String contentPath）26 MyProject \ Views \ Journal \中的ASP._Page_Views_Journal_EditIssue_cshtml.Execute（） EditIssue.cshtml：45 System.Web.WebPages.WebPageBase.ExecutePageHierarchy（）197 System.Web.Mvc.WebViewPage.ExecutePageHierarchy（）105 System.Web.WebPages.StartPage.RunPage（）17 System.Web.WebPages.StartPage.ExecutePageHierarchy （）64 System.Web.WebPages.WebPageBase.ExecutePageHierarchy（WebPageContext pageContext，TextWriter writer，WebPageRenderingBase startPage）78 System.Web.Mvc.RazorView.RenderView（ViewContext viewContext，TextWriter writer，Object instance）256 System.Web.Mvc.BuildManagerCompiledView .Render（ViewContext viewContext，TextWriter writer）107 System.Web.Mvc.ViewResultBase.ExecuteResult（ControllerContext context）291 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult（ControllerContext controllerContex t，ActionResult actionResult）13 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive（IList1过滤器，Int32 filterIndex，ResultExecutingContext preContext，ControllerContext controllerContext，ActionResult actionResult）56 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive（IList1过滤器，Int32 filterIndex，ResultExecutingContext preContext ，ControllerContext controllerContext，ActionResult actionResult）420 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters（ControllerContext controllerContext，IList1 filters，ActionResult actionResult）52 System.Web.Mvc.Async . <> c__DisplayClass2b . <BeginInvokeAction> b__1c（）173 System.Web .Mvc.Async . <> c__DisplayClass21 . <BeginInvokeAction> b__1e（IAsyncResult asyncResult）100 System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate（IAsyncResult asyncResult）10 System.Web.Mvc.Async.WrappedAsyncResultBase1.End（）49系统 . Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction（IAsyncResult的asyncResult）27 System.Web.Mvc.Controller . <BeginExecuteCore> b__1d（IAsyncResult asyncResult，ExecuteCoreState innerState）13 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate（IAsyncResult asyncResult）29 System.Web.Mvc.Async.WrappedAsyncResultBase1.End （）49 System.Web.Mvc.Controller.EndExecuteCore（IAsyncResult asyncResult）36 System.Web.Mvc.Controller . <BeginExecute> b__15（IAsyncResult asyncResult，Controller controller）12 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate（IAsyncResult） asyncResult）22 System.Web.Mvc.Async.WrappedAsyncResultBase1.End（）49 System.Web.Mvc.Controller.EndExecute（IAsyncResult asyncResult）26 System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute （IAsyncResult asyncResult）10 System.Web.Mvc.MvcHandler . <BeginProcessRequest> b __（IAsyncResult asyncResult，ProcessRequestState innerState）21 System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate（IAsyncResult asyncResult）29 System.Web.Mvc.Async.WrappedAsyncResultBase `1.End（） 49 System.Web.Mvc.MvcHandler.EndProcessRequest（IAsyncResult asyncResult）28 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest（IAsyncResult result）9 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute （）9644097 System.Web.HttpApplication.ExecuteStep（IExecutionStep step，Boolean＆completedSynchronously）155

抛出异常的行周围的代码行是：

<div class="form-group">
    @Html.LabelFor(model => model.IssueName, htmlAttributes: new { @class = "control-label col-md-2"})
    <div class="col-md-10">
        @Html.EditorFor(model => model.IssueName, new { htmlAttributes = new { @class = "form-control", id = "IssueName" } })
        @Html.ValidationMessageFor(model => model.IssueName, "", new { @class = "text-danger" })
    </div>
</div>

IMPORTANT

奇怪的是，只有当我从回发后回来时才会引发异常，从来没有在我第一次加载视图时，甚至在 ModelState 没有错误时也是如此 . 只有当 ModelState 在回发后出现错误时才会引发此问题 .

这是一些服务器端代码，但我没有看到任何可能出错的原因：

[HttpPost]
public async Task<ActionResult> EditIssue(EditIssueViewModel viewModel)
{
    viewModel.AvailableTags = BusinessManager.GetAllTags();

    if (viewModel.IssuePDFFile == null || viewModel.IssuePDFFile.ContentLength == 0)
    {
        ModelState.AddModelError("", "Please select a file to upload.");
        return View(viewModel);
    }

    var fileInfo = new FileInfo(viewModel.IssuePDFFile.FileName);
    if (!StaticData.AcceptedContentTypes.Contains(viewModel.IssuePDFFile.ContentType, StringComparer.InvariantCultureIgnoreCase) ||
        !fileInfo.Extension.Equals(".pdf", StringComparison.InvariantCultureIgnoreCase))
    {
        ModelState.AddModelError("", "You can only select a PDF file.");
        return View(viewModel);
    }

    if (!ModelState.IsValid)
    {
        var errors = ModelState.Values.SelectMany(v => v.Errors)
            .Select(e => new { e.ErrorMessage, e.Exception });

        var errorList = errors.ToList();

        errorList.ForEach(e => Debug.Print(e.ErrorMessage));
        errorList.ForEach(e => ModelState.AddModelError("", e.ErrorMessage));

        return View(viewModel);
    }

    var operationResult = await BusinessManager.EditIssueAsync(viewModel);

    if (!operationResult.Succeeded)
    {
        ModelState.AddModelError("", operationResult.FailureMessage);
        return View(viewModel);
    }

    viewModel = (EditIssueViewModel)BusinessManager.GetIssueWithRelationships(viewModel.IssueId);
    viewModel.SuccessMessage = operationResult.SuccessMessage;
    return View(viewModel);
}