https://www.bleepingcomputer.com/news/microsoft/windows-10-cumulative-updates-released-with-fix-for-file-association-bug/

Microsoft has released another cumulative update for Windows 10 with some fixes. The update is not available for Windows 10 October 2018 Update and you will see it only if you've Windows 10 April 2018 Update or Fall Creators Update installed.

To grab new updates, you can open Settings via Start menu and navigate to Update & Security -> Windows Update and select Check for updates to install the latest patch. If you would like to install the updates manually, you can download and install it from here.