Today, Windows 10 version 1903 is getting its final cumulative update, as it has reached its end of life. While this date has always been public knowledge, it may come as a surprise to those that weren't paying attention since 1809 support ended just last month.
This applies to all SKUs of Windows 10, including Home, Pro, Pro for Workstations, Enterprise, and Education. Spring updates are only supported for 18 months, while fall updates are supported for 18 months for Home and Pro SKUs, and for 30 months for Enterprise and Education. That's why if you're on Windows 10 Enterprise or Education, version 1809 is still supported until May.
Microsoft had actually extended support for Windows 10 version 1809 by six months because of the COVID-19 pandemic. That's why support for the two versions ended only a month apart.
Windows 10 version 1903 is significant because it was the first Windows 10 feature update that wasn't automatically installed on users' computers. Due to version 1809 being a mess, the Redmond firm said that feature updates would be completely optional unless the version you're running is nearing the end of support.
For version 1809, it started upgrading users to version 2004 back in June, but for 1903, Microsoft didn't start migrating users to a newer version until only a month ago. And instead of upgrading users to the newest version, it moved them to the year-old version 1909. If you're still on Windows 10 version 1903, you should be able to get to something newer by checking for updates in Windows Update. If you don't find anything there, you can use Microsoft's own upgrade tool.