Before getting into what’s changed in today’s cumulative update preview (optional update), a few important things:
With that out of the way:
October 2021 optional cumulative update for Windows 10 (KB5006738/build 19043(4).1320) is now available from Windows Update:
■ Updates an issue an issue that might prevent subtitles from displaying for certain video apps and streaming video sites.
■ Updates an issue that prevents Kana input mode users from inserting a question mark (?) using the Shift-0 key combination.
■ Updates an issue that sometimes causes your lock screen background to appear black if you have set up a slideshow of pictures as your lock screen background.
Version 21H1 (19043.1320):
■ Addresses an issue that prevents you from accessing the pre-provisioning page during the out-of-box experience (OOBE). This issue occurs when the credentials page for signing in to Azure Active Directory appears, and you press the Windows key five times.
■ Adds a feature that facilitates certain cross-browser data transfers.
■ Addresses an issue with Assigned Access kiosks that are configured with Microsoft Edge as a kiosk application. These kiosks might sometimes fail to restart Microsoft Edge if users close the browser window.
■ Addresses an issue in which the use of App-V intermittently causes black screens to appear when signing in on the credentials page.
■ Addresses an issue that might prevent subtitles from displaying for certain video apps and streaming video sites.
■ Addresses an issue that prevents Windows 10 virtual private network (VPN) users from connecting to Windows Server 2019 Routing and Remote Access service (RRAS) servers.
■ Addresses an issue that prevents Software-Defined Networking (SDN) virtual machines from working when you configure the Generic Routing Encapsulation (GRE) VPN bandwidth limitation.
■ Addresses a Primary Refresh Token (PRT) update issue that occurs when VPN users sign in using Windows Hello for Business when the VPN connection is offline. Users receive unexpected authentication prompts for online resources that are configured for user sign-in frequency (SIF) in Azure Active Directory-Conditional Access.
■ Addresses an issue that causes Windows to go into BitLocker recovery after a servicing update.
■ Addresses an issue that might cause Kerberos.dll to stop working within the Local Security Authority Subsystem Service (LSASS). This occurs when LSASS processes simultaneous Service for User (S4U) user-to-user (U2U) requests for the same client user.
■ Addresses an issue in Code Integrity that might cause a memory leak.
■ Enhances Microsoft Defender for Endpoint’s ability to identify and intercept ransomware and advanced attacks.
■ Addresses an issue in the OOBE that might cause Windows AutoPilot provisioning to fail.
■ Addresses an issue that prevents Kana input mode users from inserting a question mark (?) using the Shift-0 key combination.
■ Addresses an issue that sometimes causes the lock screen to appear black if you set up slideshow.
■ Addresses a reliability issue with LogonUI.exe, which affects the rendering of the network status text on the credentials screen.
■ Addresses an issue that causes Server Message Block (SMB) Query Directory Requests to fail when the buffer size is large.
■ Addresses a memory leak issue in lsass.exe on domain controllers in the forest root domain that occurs when you have multiple forests and multiple domains in each forest. The SID-Name mapping functions leak memory when a request comes from another domain in the forest and crosses forest boundaries.
■ Addresses an issue with the virtual machine (VM) Load Balancing feature, which ignores a site’s fault domain.
■ Addresses a known issue that might prevent the successful installation of printers using the Internet Printing Protocol (IPP).
Version 21H2 preview (19044.1320): same as 21H1.