Hey guys,

So I need a hand, I'm running up against a brick wall and I think I'm going slightly mad.

I have an Umbraco Instance with 2 sites in it (they aren't multi-lingual but are very closely related). What I'm trying to do is apply a styled, friendly, 404 error page in each site.

So, lets start with the blogs I've used for pointers:

1) https://blog.mortenbock.dk/2017/02/03/error-page-setup-in-umbraco/ This was a great article and very helpful, however a small note: I'm yet to create the fallback 404.html and 404.aspx files as I have been trying to get the content based 404's to work first.

2) https://www.diplo.co.uk/blog/web-development/404-page-finder-for-multi-site-umbraco-installations/ AND http://24days.in/umbraco-cms/2014/the-double-album/multi-site-404/ These two basically say the same thing but are focused around using a content finder to get to 404 content page.

So, my content finder class is a slight variation on the ones linked above. Instead of searching for a document type it grabs the home node and gets the value from a content picker which represents the 404 page.

As far as I can tell however, this is working. I've put various logging steps in place and the log updates saying it finds the node which I've indicated is a 404. However, sometimes I get to see the content based 404 error, other times I just get the 404 error from the server.

What I don't understand is why?

The following is my resultant Content Finder:

public class FourOhFourFinder : IContentFinder
{
    #region Implementation of IContentFinder

    public bool TryFindContent(PublishedContentRequest contentRequest)
    {
        LogHelper.Info(GetType(), string.Format("404 Finder triggered"));
        //Check request cannot be found
        if (contentRequest.PublishedContent == null)
        {
            var domain = contentRequest.UmbracoDomain;

            if (domain != null)
            {
                LogHelper.Info(GetType(), string.Format("Domain Found - Root Node: {0}", domain.RootContentId.GetValueOrDefault(0)));
                var home = domain.RootContentId.HasValue && domain.RootContentId.Value > 0 ?
                    contentRequest.RoutingContext.UmbracoContext.ContentCache.GetById(domain.RootContentId.Value) : null;

                if (home != null)
                {
                    //Get the 404 node
                    //The page not found is stored as a property on the home page.
                    var pageId = home.GetPropertyValue<int>("pageNotFound");
                    LogHelper.Info(GetType(), string.Format("404 page ID - {0}", pageId));
                    var notFoundNode = contentRequest.RoutingContext.UmbracoContext.ContentCache.GetById(pageId);
                    LogHelper.Info(GetType(), string.Format("404 page node found ? - {0}", notFoundNode != null));
                    if (notFoundNode != null)
                    {
                        //Set Response Status to be HTTP 404
                        contentRequest.SetResponseStatus(404, "404 Page Not Found");

                        //Set the node to be the not found node
                        contentRequest.PublishedContent = notFoundNode;
                    }
                }
            }
        }

        return contentRequest.PublishedContent != null;
    }

    #endregion
}

public class ContentFinderStartUp : ApplicationEventHandler
{
    protected override void ApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
    {
        ContentFinderResolver.Current.InsertTypeBefore<ContentFinderByNotFoundHandlers, FourOhFourFinder>();
    }
}

Oh yeah, another thing. It all appears to work absolutely fine on my development environment. All of this strange behaviour only occurs on the Live environment. I did think cache related, but I've tried deleting the umbraco.config, re-publishing the site from the backoffice, recycling the app-pool. All to no resolution.

Does anyone have any ideas of things I may have missed? If you need more information please let me know.

Thanks,

Nik