I have created a custom 404 handler which has been working fine up to now (for the past 2 months). It allows the content editor to create a content page within Umbraco and then select that page to be used as the 404 page.

All of a sudden we are getting intermittent 404 errors on a few pages in the site. When I look at PublishedContentRequest, PublishedContent is null. If I reload the site then it seems to be able to find the content without issues.

My code is as follows:

public class PageNotFound : IContentFinder
    {
        public bool TryFindContent(PublishedContentRequest contentRequest)
        {
            if (contentRequest.PublishedContent == null)
            {
                var url = contentRequest.Uri.GetAbsolutePathDecoded();

                var message = "Page not found: " + url;

                LogHelper.Warn(MethodBase.GetCurrentMethod().DeclaringType, message);

                contentRequest.SetResponseStatus(404, "Not Found");

                var website = UmbracoContext.Current.ContentCache.GetById(contentRequest.Domain.RootNodeId);

                if (website != null)
                {
                    var page = website.GetProperty("PageNotFoundErrorPage") != null ? website.GetProperty("PageNotFoundErrorPage").Value.ToString() : "1";
                    int errorPageId;
                    int.TryParse(page, out errorPageId);

                    contentRequest.PublishedContent = UmbracoContext.Current.ContentCache.GetById(errorPageId);
                }
            }

            return contentRequest.PublishedContent != null;
        }
    }

I can't understand why the published content is null. It's an intermittent issue so not related to site reload etc.