Asp.net-mvc – The following sections have been defined but have not been rendered for the layout page “~/Views/Shared/_Layout.cshtml”

Was given a suggestion on the ASP.net forums that works.

Essentially, if I define @section LeftCol in my view template but don't run any code that calls RenderSection in my layout, I get the error because it doesn't get called when View.ShowLeftCol is false. The suggestion was to add an else block and essentially throw away whatever contents are in the LeftCol section.

@if (View.ShowLeftCol)
{ 
<div id="leftCol"> 
    @RenderSection("LeftCol", false) 
</div> 
}
else
{
    WriteTo(new StringWriter(), RenderSection("LeftCol", false));
}

Based on the concern raised about memory I decided to test the following out as well. Indeed it also works.

@if (showLeft)
{
    <section id="leftcol">
        <div class="pad">
            @RenderSection("LeftColumn", false)
        </div>
    </section>
}
else
{
    WriteTo(TextWriter.Null, RenderSection("LeftColumn", false));
}

Also, at the top of my page, this is my new logic for showLeft/showRight:

bool showLeft = IsSectionDefined("LeftColumn");
bool showRight = IsSectionDefined("RightColumn");
bool? hideLeft  = (bool?)ViewBag.HideLeft;
bool? hideRight = (bool?)ViewBag.HideRight;
if (hideLeft.HasValue && hideLeft.Value == true) { showLeft = false; }
if (hideRight.HasValue && hideRight.Value == true) { showRight = false; }

Someone else said it didn't work for them, but it worked like a charm for me.

It means that you have defined a section in your master Layout.cshtml, but you have not included anything for that section in your View.

If your _Layout.cshtml has something like this:

@RenderSection("scripts")

Then all Views that use that Layout must include a @section with the same name (even if the contents of the section are empty):

@{
    ViewBag.Title = "Title";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
@section scripts{
    // Add something here
}

As an alternative, you can set required to false, then you won't be required to add the section in every View,

@RenderSection("scripts", required: false)

or also you can wrap the @RenderSection in an if block,

@if (IsSectionDefined("scripts"))
{
    RenderSection("scripts");
}