Quote:Microsoft plans to release an update early next year for the company's Windows 7 and Windows Server 2008 operating systems that add support for SHA-2 update handling to them.

Updates are delivered using SHA-1 and SHA-2 currently. SHA-1 is a  hashing algorithm with known weaknesses and Microsoft plans to do away with SHA-1 support in April 2019 to use SHA-2, an improved hashing algorithm, exclusively going forward.

While that is no problem for Windows 8.1, Windows 10, or the server equivalents, it is one for devices running Windows 7 or Windows Server 2008. The reason is simple: SHA-2 is not supported by these operating systems when it comes to updates.

Any update that is delivered as SHA-2 exclusively, better, signed using SHA-2, can't be verified on Windows 7 or Windows Server 2008 devices. Means, these updates don't get installed on devices running these versions of Windows anymore unless the SHA-2 update patch is installed first.

Full reading: https://www.ghacks.net/2018/11/20/running-windows-7-or-server-2008-you-will-need-this-patch/