In this article, we will talk about the latest Windows 11 Update for the 26H2 Main Release, which is the Build 26300.9711 or KB5127648.
For those of you who are not familiar with how Windows 11 Updates for the Main Release work, I will explain it to you in the following lines.
Every month Windows 11 has a B and a C Release for Windows 11. Usually, the B Release is launched on the second Tuesday of the month and contains all the features that were tested in the previous month’s C Release.
Microsoft is also announcing that starting with the January 2026 security update, Windows Server 2025 will have its own KB identifiers and build numbers. This change applies only to Windows Server 2025. It doesn’t change how you get or manage updates for Windows 11, version 24H2 or Windows 11, version 25H2.
New Improvements in this Update
- Because of minimal operations during the Western holidays and the upcoming new year, there will be no December 2026 non-security preview update in the second part of the month. Normal monthly servicing for both security and non-security preview updates will resume in January 2027.
- Secure Boot certificate updates remain in progress as Microsoft transitions devices from certificates that began expiring in 2026 to newer certificates. Devices that have not yet received the newer certificates can continue to start and receive standard Windows updates. Microsoft will continue delivering the newer Secure Boot certificates to eligible devices through Windows Update.
- [Security updates] This update provides security improvements. For more information about the security vulnerabilities resolved by this update, see the Security Update Guide.
- [Secure Boot] This update includes additional high confidence device targeting data, increasing coverage of devices eligible to automatically receive new Secure Boot certificates. Certificate deployment via Windows updates continues across supported PCs and non-managed business devices in the coming months.
- [Audio (known issue)] – Fixed: USB Audio 1.0 devices might fail to start and display error code 10 in Device Manager after installing a recent security update.
- [Printing] Fixed: Adding a printer published in Active Directory through Settings > Bluetooth & devices > Printers & scanners > Add device might fail with error 87, “The parameter is incorrect.” This issue was introduced by the October 2026 update and does not generally affect existing printers or printing.
- [Security] This update improves NTLM security by enabling clients to offer NTLM message signing by default for non-anonymous connections. This change helps reduce exposure to NTLM relay attacks and provides auditing to identify connections that are not using signing. To learn more, see NTLM signing security improvements in Windows.
- [Date and Time] This update adjusts daylight saving time (DST) rules for Cuba for the extended 2026-2027 DST period. Cuba remains on UTC-04:00 and doesn’t observe the November 2026 and March 2027 transitions. It returns to UTC-05:00 in November 2027 and resumes its regular seasonal schedule in 2028.
- For the latest DST and time zone guidance, see the Daylight Saving Time & Time Zone Blog.
- [Remote Desktop] This update addresses an issue where Remote Desktop Protocol (RDP) connections might fail on the client due to a certificate mismatch after the October 2026 non-security preview update.
- [Windows PowerShell] This update strengthens security for PowerShell script signing and signature verification by introducing stricter encoding validation. As a result, scripts containing invalid UTF-8 encoding might fail signature validation, even if they were previously accepted. To resolve this issue, review the affected scripts, save them using valid UTF-8 encoding with a byte order mark (BOM), and sign them again. For further guidance, see Encoding Guidance for Signed PowerShell Scripts.
- Rolling out with the November 2026 update: The new Restore summary in Windows 11 shows which settings and Microsoft Store app listings were restored from your backup profile, helping you continue setup on a new device with confidence. Learn more here.
For an in-depth list of other features and fixes that are rolling out, you can check this article.
For more info about this Update, you can check this article from the Microsoft Blog.
For a more in-depth presentation of the New Update, you can watch the video below from the YouTube channel.
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