If you have not installed Sitefinity v. 4.x before, you may not know that there are some specific configuration IIS settings that need to be configured prior to deployment that differ from the original IIS configuration requirements in Sitefinity v. 3.7x. If you do not configure them, you will experience numerous error messages preventing you from accessing and using Sitefinity.
- Make sure you configure the Sitefinity Web Site/Application to point to a .Net 4.0 Application Pool
- Make sure that you configure the Authentication settings for only a single authentication method. The recommended authentication method is "Anonymous access". If you have more than one authentication method configured in IIS, you will experience a pop-up dialog preventing you from accessing the Sitefinity administrative backend.