Microsoftは7月28日(現地時間)、Windows 11 Version 26H1用のプレビューアップデートKB5101681を公開しました。オプション扱いの更新プログラム(プレビュー版)で、多数の不具合が修正されています。Windows Updateの「更新プログラムのチェック」を利用するか、Microsoft Update Catalogからファイルをダウンロードすることで、手動でインストールすることができます。July 28, 2026—KB5101681 (OS Build 28000.2608) PreviewWindows 11 Version 26H1用の更新プログラムKB5101681では、Windows Updateの一時停止期間をカレンダーで指定できる新機能が追加されています。最大35日間の停止が可能で、終了日を変更することで延長もできます。ウィジェットの通知を控えめにする改良やアクセシビリティの強化、ファイルエクスプローラーの操作性向上も行われています。リリースノートは以下の通りです。ハイライトGradual rolloutThe following summary outlines features from AI-powered Windows 11 PC experiences, along with improvements and fixes. The bold text within the brackets indicates the item or area of the change.Windows 11 PC experiencesThis section highlights some new features and enhancements for Windows 11 PCs, including AI-powered capabilities, continuous innovation, and performance improvements.Windows UpdateNew! A calendar experience in Windows Update Settings (Settings > Windows Update) lets you pause updates by choosing an end date, for up to 35 days. You can extend the pause by selecting a different end date and re‑pause updates as needed. For more information, see Pause updates in Windows.WidgetsNew! A quieter, more focused Widgets experience helps reduce interruptions and improves default settings and notification controls:Reduce distractions: Widgets no longer open on hover. Notifications and taskbar badges are minimized by default.Simpler: Open to the Widgets dashboard by default on first use.Customize: Configure Widgets how you want by selecting Settings in the navigation bar, then changing any of the default settings.Stay informed: Dashboard icons show the number of alerts, and badges clear automatically when you leave a dashboard.Adjusted defaults: Some default settings are preserved based on usage, while others adjust to reduce interruptions.Performance improvements: This update provides improved reliability, responsiveness, and visual quality across the Widget experience.AccessibilityNew! This update makes your screen easier to see and customizes your zoom experience:Screen tint: Apply a full-screen color overlay to help reduce eye strain and improve readability. Choose from preset tint options, adjust the intensity, or turn it on automatically. Find this feature in Settings > Accessibility.Magnifier: Enter a zoom percentage directly and change it in increments in the Magnifier window for more precise, flexible control.Magnifier settings menu: You can now also modify zoom increments directly from the magnifier bar instead of navigating to Windows Settings each time.File ExplorerNew! When you hover over a file in File Explorer Home, commands such as Open file location and Ask Copilot appear as quick actions. This experience is now supported for work and school accounts (Entra ID).1Improves the speed and performance of File Explorer launch.2This update improves File Explorer responsiveness when mounting disk images.The address bar now supports paths containing double backslashes and quotation marks (for example, C:\Users\user or "C:\Users\user"), improving compatibility with a wider range of inputs.The address bar suggestion dropdown is more reliable and now consistently closes after an item is selected.This update addresses an issue on File Explorer Home where OneDrive files could appear duplicated in the Favorites section.This update includes several refinements to the Rename experience:Addresses an issue where text was repeatedly selected when renaming items in folder views.Addresses an issue where case-only name changes were not immediately reflected in folder views for items stored locally or in the cloud.BluetoothThis update improves reliability and performance when connecting to and using Bluetooth devices:New! Windows now keeps the microphone mute state in sync between the audio mixer and the Hands-Free Profile (HFP) for a more consistent experience with Bluetooth headphones with mute buttons or indicators.Accessory compatibility workarounds: Improves compatibility with specific Bluetooth audio devices, helping AirPods appear faster in pairing mode and improving microphone reliability on Beats Studio Pro headphones.Bluetooth audio stability:Improves overall Windows stability with certain PC manufacturer drivers (error code 0x9F).Improves Bluetooth reliability for voice calls when using Classic Audio devices with the Hands-Free Profile (HFP).Reduces time for LE Audio accessories to start playing audio while using the microphone.Device management: Windows will no longer show a “Remove failed” message when attempting to remove Bluetooth devices if the Bluetooth radio is unavailable or has changed since pairing.Settings experience: Improves stability when using the Bluetooth & devices settings page for a smoother, more consistent experience.Connection reliability and responsiveness:Reduces the time it takes for classic Bluetooth audio devices to reconnect after Windows resumes from hibernation.Improves reliability when LE Audio accessories disconnect, such as when another device (for example, a phone) connects.Improves reliability of LE Audio streaming after a connection is lost and restored.Bluetooth and Phone LinkThis update improves audio routing for calls made through a connected phone:When an outgoing call is dialed from a paired phone, audio remains on the phone while ringing and transfers to the PC only when the call is answered from the PC.When Do Not Disturb is enabled on Windows, incoming call audio from a paired phone no longer rings on the PC.Voice access and voice typingNew! You can now use voice access and voice typing in French, German, and Spanish. As you speak, your PC improves your text in real time. It corrects grammar, punctuation, and recognition errors, and helps improve clarity—even in the presence of background noise. This makes dictation smoother and reduces the need for manual edits.3AudioThis update improves the reliability of the inbox HD Audio driver.TaskbarThis update improves the reliability of opening the Start menu when selecting the left edge of the taskbar when the icons in the taskbar are left-aligned.NetworkingThis update includes networking improvements for virtualized environments. Confidential Virtual Machines (CVMs) now use SR-IOV hardware acceleration by default for improved network throughput, and a configuration issue in nested Hyper-V virtualization network setup has been corrected to ensure reliable VM network provisioning.This update improves the reliability of the Windows networking stack. It reduces bug checks (blue screen errors) related to Wi-Fi power and improves cellular (WWAN) connectivity, including support for IPv6 VPNs. Compatibility with third-party VPN software and SR-IOV configurations on server hardware is also improved. Network adapter settings and bindings are now preserved across OS upgrades.PrintingNew! New printer installations use Internet Printing Protocol (IPP) by default when supported, simplifying setup and improving reliability. For details about third-party driver deprecation, see End of Servicing Plan for Third-Party Printer Drivers on Windows. To control this behavior, use the toggle in Settings > Bluetooth & devices > Printers & scanners > Default install printers using Windows Ready Print. For more information, see Introducing Windows Ready Print and modernized driver selection. For more information, see Introducing Windows Ready Print and Modernized Driver Selection.Windows Subsystem for Linux (WSL)The update improves usage of WSL in mirrored networking mode with VPNs.Display and graphicsImproves the reliability of rendering content while scrolling for certain apps spanning across multiple monitors.Improves the reliability and persistence of applying color profiles.Location servicesThis update changes how some location settings are displayed in Settings > Privacy & Security > Location to help with clarity. When location services are turned off, settings like Default location and Allow location override don't immediately apply, since location information is not given to apps or services. These settings will now be greyed out when location services are off to reduce confusion over when they take effect.SearchThis update improves the reliability of setting Search related group policies.InputNew! You can now customize the size of the right-click zone in Settings > Bluetooth & devices > Touchpad. Choose from default, small, medium, or large to control how much of the bottom-right corner responds to a single-finger right-click. This setting is only available on touchpads with a pressable surface. If your device manufacturer provides customization through their own app, a Custom option will appear to reflect those settings.This update improves recognition of English characters when using Japanese handwriting.General performanceImproves the time to shut down Background Intelligent Transfer Service (BITS) when you turn off your PC.General reliabilityThis update improves the reliability of explorer.exe. It addresses issues on the login and lock screens related to third-party credential providers, reduces the probability of taskbar icons appearing as blank gray placeholders, and improves navigation to Home in File Explorer during OneDrive sync. It also improves explorer.exe reliability when switching between desktops, enhances app launch with shell extensions, and using acrylic blur effects in the Start menu, Settings, and the lock screen.AppsResolves an issue where some installers and applications could show unexpected elevation (UAC) prompts after installing KB5089549.Remote DesktopThis update refreshes the dialog design when you enable Remote Desktop in Settings > System > Remote Desktop.Graphics KernelImproves memory-management policy that allows PCs with more than 32GB of installed memory to run larger local AI models.1Feature availability varies by device and market.Normal rolloutThis non-security update includes quality improvements. The following summary outlines key issues addressed by the KB update after you install it. Also, included are available new features. The bold text within the brackets indicates the item or area of the change.AppsThis update improves reliability for some Win32 applications by preventing crashes that could occur when creating a new project.File ExplorerThis update addresses an issue where files stored on a DFS mapped drive could be incorrectly treated as originating from the Internet after the device started while disconnected from the network and later reconnected. This could cause File Explorer’s Preview Pane to display the message, “The file you are attempting to preview could harm your computer,” or cause files copied from the DFS drive to receive an unexpected Mark of the Web.This update enhances File Explorer to display all characters in search results and tooltips for files using GB18030 or UTF-8 (without byte order mark) encoding.Mobile device management (MDM)This update addresses an issue affecting newly provisioned or newly recovered Windows devices running versions of Windows released on or after July 14, 2026 (KB5101649). After enrollment in a mobile device management (MDM) service such as Microsoft Intune, affected devices could remain in an incorrect noncompliant state and be unable to access corporate resources.PowershellThis updates the PowerShell application name to Windows PowerShell, restoring the previous naming to improve compatibility with applications and tools that rely on the original name.StorageThis update fixes an issue that affects File History automatic backups to network shares using Server Message Block (SMB). Backups did not work because Windows showed a false “invalid credentials” error when connecting to SMB shares.If you installed earlier updates, your device downloads and installs only the new updates contained in this package.既知の不具合更新プログラムには既知の不具合は存在しません。更新プログラムはWindows Updateの他、Microsoft Update Catalogを利用してインストールすることができます。