Microsoft has announced that only Secure Hash Algorithm 2 (SHA-2) code-signing will be used to update legacy versions of Windows (namely Windows Server 2008 SP2, Windows Server 2008 R2 SP1 and Windows 7 SP1). Machines that only support SHA-1 will be considered too vulnerable, and will be prevented from updating by next April.
https://www.notebookcheck.net/Devices-that-run-legacy-Windows-versions-and-support-SHA-1-will-be-blocked-from-updating-in-2019.366581.0.html