System.Web.WebPages.WebPageBase.VerifyRenderedBodyOrSections C# (CSharp) Method

        private void VerifyRenderedBodyOrSections()
        {
            // The _body will be set within a layout page because PageContext.BodyAction was set by RenderSurrounding, 
            // which is only called in the case of rendering layout pages.
            // Using RenderPage will not result in a _body being set in a partial page, thus the following checks for
            // sections should not apply when RenderPage is called.
            // Dev10 bug 928341 
            if (_body != null)
            {
                if (SectionWritersStack.Count > 1 && PreviousSectionWriters != null && PreviousSectionWriters.Count > 0)
                {
                    // There are sections defined. Check that all sections have been rendered.
                    StringBuilder sectionsNotRendered = new StringBuilder();
                    foreach (var name in PreviousSectionWriters.Keys)
                    {
                        if (!_renderedSections.Contains(name))
                        {
                            if (sectionsNotRendered.Length > 0)
                            {
                                sectionsNotRendered.Append("; ");
                            }
                            sectionsNotRendered.Append(name);
                        }
                    }
                    if (sectionsNotRendered.Length > 0)
                    {
                        throw new HttpException(String.Format(CultureInfo.CurrentCulture, WebPageResources.WebPage_SectionsNotRendered, VirtualPath, sectionsNotRendered.ToString()));
                    }
                }
                else if (!_renderedBody)
                {
                    // There are no sections defined, but RenderBody was NOT called.
                    // If a body was defined, then RenderBody should have been called.
                    throw new HttpException(String.Format(CultureInfo.CurrentCulture, WebPageResources.WebPage_RenderBodyNotCalled, VirtualPath));
                }
            }
        }