Application status pages display workflow
On system start or upgrade the user is redirected to http://<your-site>/sitefinity/status where the application status page is rendered. In case the application is already running and user accesses this URL, automatic redirect to the ReturnUrl is executed. In case there is no ReturnURL, the user is redirected to the home page.
The following diagram illustrates how Sitefinity CMS displays different status pages:

