Problem: Used the upgrade utility within the WordPress dashboard to upgrade to the latest version. Once I upgraded I couldnâ€™t access my site. It would come up to a page that said the following:
Briefly unavailable for scheduled maintenance. Check back in a minute
Solution: I had to delete the .maintenance file in the root of the web and then I was fine. The problem had to do with my security settings within IIS7. My user was not allowed to delete the file it created.