Microsoft has begun informing users that the 1903 version of Windows 10 reaches the end of support next month and those who are still running the unsupported operating system will be forced to upgrade.
Earlier this year, Microsoft announced that the 1903 version of Windows 10 reaches support end in December. Thus it will receive the final cumulative update on December 8, 2020.
In the coming weeks, Microsoft will begin to forcibly upgrade those running version 1903 of Windows 10 to a newer compatible version, such as version 1909. If your device is not ready for version 2004 or the latest 20H2, it will not be upgraded beyond From the 1909 edition.
If you are already using version 1909, you will need to upgrade to version 2004 in May 2021.
Be aware that you can now skip the upgrade block to a version or specify the version of Windows 10 you want to use making some changes in Group Policy Editor or Registry Editor.
Microsoft says about the upgrade block:
Not all features in one update work on all devices. Similarly, a device may not be able to receive updates if the device hardware is incompatible, does not have current drivers, does not have enough storage space, or is alternatively out of the original equipment (OEM) support period. For more information on compatibility, see Windows 10 System Requirements as well as on Windows Editor Requirements.
The support fee only applies to those using Windows 10 Home and Pro. Microsoft will continue to support Windows 10 Enterprise and Education users for a year or two.
It is also worth noting that a large number of users still use Windows 10 in version 1903 for a number of reasons. The majority did not upgrade to the 1909 version or the 2004 / 20H2 version due to the mysterious upgrade blocks imposed by Microsoft.
Later, Microsoft plans to expand the availability of Windows 10 version 20H2, also known as the October 2020 Update. In the first half of 2021, another service pack style upgrade called Windows 10 21H1 will be released to consumers.
Windows 10 version 21H1 will replace version 20H2 with fixes and enhancements. According to reports, Microsoft will add new features to upgrade to Windows 10 "Sun Valley", which is expected to be released in the second half of next year.