Azure DevOps pipeline agent operating system deprecation: Windows Server 2019 out by end of year

Microsoft recently announced that they will be deprecating Windows Server 2019 agent host image (the operating system version running your pipelines). Exact schedule can be found here.

Windows Server 2019 support has originally planned to be fully deprecated by end of this month (October, 2025), but that deadline was postponed to the end of this year (2025). This is of course good news.

In addition to Windows Server 2019, also Ubuntu version 20 was also deprecated earlier, in April.

Note that this time too, like before, Microsoft will do what is called a "brownout": for a short moment, they will make the soon-to-be-deprecated agent host versions unavailable to raise awareness. This way, build pipelines using older operating system versions will fail, but return to normal operation once the brownout period ends. These usually last about 6–8 hours.