Microsoft has ended support for Windows 10 version 1803 'April 2018 Update' for Home and Pro users. These editions are no longer supported. Microsoft suggests users of these editions to go with Windows 10 version 1903.
Earlier, Windows 10 version 1803 was showing upgrade notifications, along with tips to upgrade the OS when visiting the Windows Update page. The exact date when Windows 10 April 2018 Update reaches end of service is November 12, 2019 for both Home and Pro editions. Instead of forcing the update right away, Microsoft has started showing a warning.
Microsoft plans to start enforcing updates on devices running Windows 10 version 1803 if you haven't updated already to a recent version by the time it reaches end of support. So, don't be surprised if your Windows 10 version 1803 is automatically upgraded to version 1903 in a few days.
Interested users can go to Windows 10 version 1909, a newer version of Windows 10 that is available for download and can be installed manually via Windows Update.
It is worth mentioning that Enterprise or Education SKUs will be supported for one more year.