Microsoft released KB4492978 update package for Windows 10 October 2018 Update (version 1809) and Windows Server 2019 (1809) on the Release Preview channel. After the upgrade, the Windows 10 build number changes to 17763.349.
A cumulative update KB4492978 has become available to members of the Windows Insider program with the priority of receiving updates of the Preview Preview. The update is intended for Windows 10 version 1809 (October 2018 Update) based on x86, x64 (amd64), ARM64 and Windows Server 2019 (1809) processors for x64-based systems.
Installation via Windows Update
Cumulative update 4492978 for PC is installed automatically through Windows Update. To check, go to Options > Update and Security and click Check for Updates. To complete the installation, you will need to restart the computer. After the upgrade, the Windows 10 build number will change to 17763.349.
Download update KB4492978 (Build 17763.349)
At the moment, you can also download the update and install it manually only using the CAB files from the official Microsoft server.
Cumulative Update for Windows 10 Version 1809 & Windows Server 2019 KB4492978 (17763.349):
direct MS-links (Thanks MDL!)
— Diamond Monday (@DiamondMonday) March 7, 2019