Ahead of the April 30 official launch, Microsoft is now rolling update KB4135051 for Windows 10 version 1803 (April 2018 Update). This is a small update currently available only for PCs enrolled in the Fast, Slow, and Release Preview rings of the Windows Insider Program.
KB4135051 bumps the version number of Windows 10 to build 17134.5, but it’s unclear the fixes and improvements the update address as Microsoft hasn’t yet released any more details.
While this update is currently only available as a cumulative update for Insiders, everyone else will be able to install the update starting April 30, when the update becomes officially available using the Media Creation Tool and Update Assistant. Also, Microsoft plans to roll out the new version through Windows Update on Tuesday, May 8, 2018.
How to download the April 23 update for Windows 10
Windows 10 build 17134.5 (KB4135051) for PCs is available immediately. The new update will download and install automatically, but you can always force the update from Settings > Update & Security > Windows Update and clicking the Check for updates button.