Steve's Windows 10 machine won't update beyond 1803. Leo says that Microsoft pulled 1809 because of some bugs. It will be fixed and available again soon, though. Feature updates aren't critical — it's just the security updates that are important. But if it's preventing him from getting security updates, then it could mean the update is blocked and he'll have to clear 1803 in order to get back to updating. Microsoft has a troubleshooter for blocked updates, and Leo recommends running it. He can get it at support.microsoft.com (here).