March Patch Tuesday for Windows 7 brought new updates to support the SHA-2 encryption algorithm.
These updates must be installed before the 16 July 2019, on the Windows 7 Service Pack 1 operating systems and on the Windows 2008 R2 Service Pack 1 operating systems before they can receive subsequent updates after that date.
You will find them through Windows Update on all Windows 7 and Windows Server 2008 devices as part of the Patch Tuesday of this month. If you do not install them, you will not be able to have any other security updates since July.
The KB4474419 update introduces SHA-2 support for Windows 7 SP1 and Windows Server 2008 R2 SP1 while KB4490628 is an update that resolves an issue associated with this hash algorithm. This technically means that Windows Update will be ready to receive updates signed with the SHA-2 algorithm, so your device will complete the downloads and update facilities without any problems.
Finally, KB4484071 is an update that specifically targets the Windows Server Update Service 3.0 service pack 2 (WSUS).
Company-based updates will be included in the next Patch Tuesday, while Windows users will be able to download and install them manually from the Microsoft Update Catalog.