This update includes quality improvements and security fixes. No new operating system features are being introduced in this update. Key changes include:
- Improved reliability of Windows Media Player, Internet Explorer 11, Windows Explorer, Miracast, and Windows kernel.
- Fixed issue with some people seeing a black screen instead of the lock screen when resuming from connected standby.
- Fixed issue with DirectAccess where the Disconnect button appears in some cases when the connection isn't fully established.
- Fixed issue where local user accounts weren't locked after a number of failed sign in attempts.
- Improved support for video playback in certain apps that didn't render video correctly after resuming from sleep.
- Fixed issue with Windows Phone losing user authentication certificates after upgrading to Windows 10 Mobile in some cases.
- Improved support of the backup settings of apps on Windows 10 Mobile.
- Fixed issue where Microsoft Silverlight based apps wouldn't install on Windows 10 Mobile after joining Azure Active Directory.
- Fixed additional issues in .NET, Windows Kernel, Windows Update, authentication, revised daylight saving time, support for PDF files, Bluetooth, Microsoft Edge, Internet Explorer 11, networking, and Wi-Fi connectivity.
- Security updates for Microsoft Edge, Internet Explorer 11, Kernel Mode Drivers, Windows Kernel, .NET Framework, Windows Secure Kernel Mode, and Microsoft Print Spooler.
For more info about security fixes in this update and a complete list of affected files, see KB3172985