This update includes quality improvements. No new operating system features are being introduced and no new security updates are included. Key changes include:
Fixed issue that may cause backups to not work because it appears there isn't enough disk space on the target volume, even when there is enough space for the backup.
Addressed issue in Microsoft Secure Channel (SChannel) that sometime causes Transport Layer Security (TLS) 1.2 connections to fail depending on whether the root certificate is configured as part of the certificate chain for server authentication.
Extended support of the Key Management Service (KMS) for Windows 8 and Windows Server 2012, in order to enable the activation of clients running Windows 10 Anniversary Update-based long-term servicing branch (LTSB) and Windows Server 2016 clients, when they become available.
In addition to installing this update on the KMS Host, a KMS generic volume license key (GVLK) that is designed to support the Windows 10 Anniversary Update-based LTSB or Windows Server 2016 clients also needs to be installed. Information about the associated KMS GVLKs for these products will be listed inAppendix A: KMS Client Setup Keys, when they become available.
The KMS GVLKs that support the new versions of Windows will also support previous volume licensing editions of Windows that are acting as KMS clients. For more info about using a Customer Support Volume License Key (CSLVK) for installation, see this article.
For more info about how to get this update and a complete list of affected files, see KB3172615.