Hello,

Suddenly on our production environment preview stopped working. On our acceptance environment it is working. It has worked before, so I'm not sure why it stopped working.

On the healthcheck I saw the XML Data Integrity had errors, but after fixing that the preview still didn't work.

The preview does some special tricks you can read about here: http://24days.in/umbraco-cms/2016/umbraco-edge-case-stories/#preview

Even though we do some special tricks it should still work. Pages without a ContentFinder and UrlProvider do work so that is the first thing I investigated. Most of them look like this:

public string GetUrl(UmbracoContext umbracoContext, int id, Uri current, UrlProviderMode mode)
{
    var targetPublishedContent = umbracoContext.ContentCache.GetById(id);

    if (targetPublishedContent != null)
    {
        Models.ContentModels.Language language;
        var contentRepository = DependencyResolver.Current.GetService<IContentRepository>();

        language = !umbracoContext.IsFrontEndUmbracoRequest
            ? contentRepository.GetAllLanguageContainers().FirstOrDefault()
            : contentRepository.GetCurrentLanguageContainer();

        if (language != null)
        {
            return umbracoContext.UrlProvider.GetUrl(language.Id).EnsureEndsWith("/")
                    + this.GetUrlSegment(targetPublishedContent, language.GetCultureCached().Name);
        }
    }

    return null;
}

I think somehow targetPublishedContent is null and that is why it isn't returning the URLs. Any idea what this could happen and only on production?

I'm using Umbraco 7.5.3. Could an upgrade to 7.5.6 help?

Jeroen