https://wccftech.com/fix-this-pc-cant-be-upgraded-install-windows-10-may-2019-update/

Microsoft has delayed the public release of its upcoming Windows 10 version 1903 to the next month. However, interested users can get their hands on this newest version before anyone else by getting enrolled in the Release Preview ring. As reported last night, it’s a pretty straightforward process that enables you to install Windows 10 May 2019 Update.

Some users have since reported that they are receiving the following alert when trying to upgrade their machines to the latest version: