The latest version of the long-running Windows operating system family is Windows 10, and Microsoft really wants consumers and businesses to leave older versions behind. The software giant has put the last nail in the coffin for the Windows XP operating system. Extended support for Windows Embedded POSReady 2009, which was the last supported version of Windows XP, ended on April 9, 2019. That marked the end of the Windows NT 5.1 product line that ran for over 17 years.
With the NT 5.1 family considered, XP was the longest-lived version of the Windows operating system. While the average consumer doesn't care about Windows NT 5.1, it hanging around for so long meant that XP Home and Pro SP3 users were still able to get security updates via a registry hack to trick Microsoft's upgrade servers. Microsoft knew of the registry hack for a long time and made no move to block its use. For those languishing on Windows XP systems, there is no direct upgrade path to Windows 10.
With official support for the last version of Windows XP over, it's unclear when or if Windows Update services for POSReady 2009 will be deactivated. TechRepublic points out that Windows Update will require machines to use SHA-2 encryption support as of July 16, 2019; XP users are expected to be able to apply any exiting updates, using the registry hack, until that date. Windows XP was very popular in its day, and as late as 2015 it still had more users than Windows 8.x boasted. Hopefully, the British Royal Navy has upgraded its HMS Queen Elizabeth warship, which launched in 2017 while still running Windows XP systems.