Windows Me

Windows Millennium Edition was released in 2000 after Windows 98. It was based on the Windows 9x/DOS architecture and was often called the "home edition" of Windows 2000.

Windows ME was criticized for its instability and the fact that Windows 2000, which came earlier that year, was much superior. Therefore, it is one of the most hated Windows versions, resulting in nicknames like "Mistake edition",

Upgrade support
Windows ME supported upgrading from Windows 95 and 98. Although Windows ME does not support upgrading from Windows 3.1, a hack was made (which involved Windows 98 license files) to allow upgrade to Windows ME.

With Windows 2000
Upgrading to ME from Windows 2000 is not possible, despite the fact that Windows 2000 is compiled earlier than Windows ME , whereas Windows ME is based on the 4x series(Windows 95 codebase) , Windows 2000 is based on the NT series(5x series). However, Windows ME can be upgraded to Windows 2000