usync blank site front page showed up in error

[SATC-Ben]

Using usync: 11.2.0 umbraco: 11.4.0 The following page was displayed on our high-traffic site over the weekend. Once the site was restarted, the site went back to normal. This is most likely a failure with Umbraco that might cause this but I'd really like to understand, how I could prevent this page from showing up on issues. Or even being able to replace it with something more brand-friendly. Are you able to give me any insight as to what the factors are that might have led to this page showing up?

[KevinJump]

Hi,

To show this screen uSync has only changed a 'NoNodes' setting (see https://github.com/KevinJump/uSync/blob/b2ffa7e75841433a6a3185474bc5af0a6fc6e1c0/uSync.BackOffice/Boot/uSyncBootExtension.cs#L31-L38 )

Control over whether or not this page actually shows is controlled by Umbraco.

So if Umbraco thinks it has no content it will render this page.

// Check if there is no existing content and return the no content controller
if (!umbracoContext.Content?.HasContent() ?? false)
{
    return new RouteValueDictionary
    {
        [ControllerToken] = ControllerExtensions.GetControllerName<RenderNoContentController>(),
        [ActionToken] = nameof(RenderNoContentController.Index),
    };
}

(https://github.com/umbraco/Umbraco-CMS/blob/b923c3252537468a7ecad2d394f37c0dbc7387ae/src/Umbraco.Web.Website/Routing/UmbracoRouteValueTransformer.cs#L189-L197)

Looking into that the HasContent method is returns true if there is any content in the published cache, so it would appear for some reason that your site temporally thought it had no published content ?

I am not sure how this might occur, but i think either the content is being cleared somewhere ? or somehow loading that content failed ? I suspect restarting the site will have reloaded the content cache.

[SATC-Ben]

Brilliant, thanks a lot.

The issue occurred in Azure so I would say the cache was inaccessible temporarily from a SaaS issue or instance upgrade but otherwise functioned correctly.

I'll take it up with Umbraco to see if there is a way this can be detected and a cache rebuild triggered.