Windows 10 may fail to download and install the cumulative updates (monthly updates) or Windows Defender virus definitions. If you are experiencing issues with Windows Update or you have multiple PCs, you might want to use the Windows Update Catalog to install updates manually. In this guide, we explain the steps required to install Windows 10 cumulative updates manually if you are unable to do so via the normal Windows Update procedure. You have to select the correct version after verifying your system configurations from Settings > System > About.
Source: https://www.bleepingcomputer.com/news/microsoft/how-to-manually-install-windows-10-cumulative-updates/