Microsoft has stopped delivering updates for Windows 7 and 8.1 operating systems running on modern processor models. Microsoft announced its intentions in January 2016, and then in March and August of the same year. The company never announced a specific deadline for this move. Microsoft says support for new CPU models will only be provided for Windows 10, its latest OS, and not Windows 7/8.1, which are approaching their end-of-life. Microsoft recommends owners of newer CPU models to update to Windows 10.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-stops-updates-for-new-cpu-models-on-windows-7-and-8-1/