https://www.bleepingcomputer.com/news/microsoft/windows-10-1903-update-blocked-by-old-intel-rapid-storage-drivers/

Microsoft has placed a compatibility hold on Windows 10 devices that prevents them from upgrading to Windows 10 1903 if they are using older Intel Rapid Storage Technology drivers. This is because certain versions of the software could cause Windows 10 to crash or not operate properly in version 1903.

If a Windows 10 user has Intel Rapid Storage Technology (Intel RST) driver versions between 15.1.0.1002 and 15.5.2.1053 installed, Windows 10 will not upgrade to version 1903. Instead, a user with this compatibility hold will see a message stating: