Microsoft has announced the retirement of Windows 10 version 1511. From ITWorld.com:
Microsoft will in two weeks finally retire a 2015 version of Windows 10, marking 29 months of support for the untitled feature upgrade, nearly as long a stretch as the time between the releases of Windows 8 and Windows 10.
Windows 10 1511 – Microsoft labels its feature upgrades in a yymm format – will receive a final set of security patches on April 10…
Microsoft has tried to inform customers of the support due them by reminding them in January’s and February’s cumulative updates that patches end for Enterprise and Education, version 1511. “The additional servicing offer for Windows 10, version 1511 ends on April 10, 2018, and doesn’t extend beyond this date. To continue receiving security and quality updates, Microsoft recommends updating to the latest version of Windows 10,” the March documentation said.
In my experience, a lot of Windows 10 users are still on version 1511 – many having turned off the mildly irritating automatic updates over the past few years. Don’t get caught with your pants down after the cutoff date; if you’re in an enterprise environment, make sure your Windows workstations are being upgraded to version 1709.