Microsoftは8月29日(現地時間)、Windows 11 Version 24H2用のプレビューアップデートKB5064081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。August 29, 2025—KB5064081 (OS Build 26100.5074) PreviewWindows 11 Version 24H2用の更新プログラムKB5064081では、通知センターの日付とカレンダーの上に表示される時計(秒付き)が復活しました。このオプションをオンにするには、[設定] > [時間と言語] > [日付と時刻]で、[通知センターに時刻を表示]をオンにします。また、Windowsのタスクバーから検索を使用する場合、グリッドビューが表示され、迅速かつ正確に目的の画像を識別できるようになりました。ロック画面やファイルエクスプローラーに関する変更も行われています。リリースノートは以下の通りです。ハイライトGradual rolloutA gradual rollout distributes a release update over a period of time instead of all at once. This means that users receive the update at different times, and it might not be immediately available to all users.[Recall]New! Recall opens to a personalized homepage that puts your recent activity and top-used apps and websites front and center, making it easy to pick up where you left off. After turning on snapshot collection, the homepage highlights key productivity features like Recent Snapshots, which show the latest snapshots to help you quickly resume tasks, and Top Apps and Websites, which display the three apps and websites you’ve used most in the past 24 hours. You can set filters in Settings to control which apps and websites are saved in snapshots. A new navigation bar on the leftmost side of the screen provides quick access to Home, Timeline, Feedback, and Settings.[Click to Do] New! When you launch Click to Do for the first time, you'll see a quick interactive tutorial. It shows how to complete tasks faster by demonstrating actions on both text and images—such as summarizing large blocks of text or removing image backgrounds. To revisit the tutorial later, select More options > Start tutorial.[General] New! When an app requests access to location, camera, microphone, or other device capabilities, Windows shows a redesigned system dialog box. To emphasize the privacy prompt, the screen dims slightly, and the prompt appears at the center of the screen.[Taskbar] New! The larger clock with seconds is now back in the notification center, displayed above the date and calendar. To turn this option on, go to Settings > Time & language > Date & time, and turn on Show time in the Notification Center.Fixed: If you accidentally click and drag your mouse across the taskbar preview thumbnail, the preview might stop working.[Search on the Taskbar] New! When you use Search from the Windows taskbar, a new grid view will help you more quickly and accurately identify the desired image within your search. New! Search on the taskbar now provides clearer status information. If your search results are incomplete while your PC is organizing files in the background, Windows shows a notice with a link to check progress. You can dismiss the notice when you're done. There is also a status for files and folders, so you can easily tell whether they’re available online (cloud) or stored on your device.[Lock screen]New! More widget options and support for lock screen widget personalization (previously referred to as “Weather and more”) are rolling out. After initial launch with Windows Insiders in the European Economic Area (EEA), these updates are expanding to all regions. You can add, remove, and rearrange lock screen widgets such as Weather, Watchlist, Sports, Traffic, and more. Any widget that supports the small sizing option can be added. To customize your lock screen widgets, go to Settings > Personalization > Lock screen.[File Explorer] New! Dividers now separate top-level icons in the File Explorer context menu. New! When you're signed in with a work or school account (Entra ID), File Explorer will display people icons in the Activity column and the Recommended section at the top of File Explorer Home. Hover over or select a person's icon to open their Microsoft 365 Live Persona Card, which shows who they are and how they're connected to the file.Fixed: If you try to use the unblock open in Properties for a file, it still shows as blocked when you open Properties the next time.[Windows Hello] New! As part of the enhanced passkey features released in September 2023, you’ll see a redesigned Windows Hello interface. These modernized visual updates support fast, clear communication that appear across multiple authentication flows, including the Windows sign-in screen, passkey, Recall, the Microsoft Store, and more. The Windows security credential experience for passkey offers a cleaner, more intuitive interface designed to support fast, secure sign-in. You can now easily switch between authentication options such as passkeys or connected devices.Fixed: Windows Hello might recognize your face on the login screen, however it would still fail and then prompt you to enter your pin. If you continue experiencing issues, you might need to go to the Facial Recognition section under Settings > Accounts >Sign-in options and select Improve recognition.Improved: Fingerprint login after standby is now more robust.[Settings] New! Windows activation and expiration prompts match the Windows 11 design and appear as system notifications when action is required. There also have been improvements to messaging under Settings > System > Activation. New! You can go to Settings > Privacy & security > Text and Image Generation to see which third-party apps have recently used generative AI models provided by Windows. You can also choose which apps are permitted to use them—putting you in charge of your device’s AI experience. New! As part of the Copilot+ PC experience, the agent in Settings helps you quickly find and change settings. Initially available on Snapdragon®-powered Copilot+ PCs, agent in Settings now supports AMD- and Intel-powered Copilot+ PCs. It currently works only when your primary display language is set to English.Fixed: Settings might crash if you attempt to add a security key under Settings > Account > Sign-in options.[Task Manager]New! Task Manager now uses standard metrics to show CPU workload consistently across all pages, aligning with industry standards and third-party tools. If you prefer the previous view, you can enable a new optional column called CPU Utility in the Details tab to display the earlier CPU usage value shown on the Processes page.[Widgets] New! Multiple dashboards are now available in your Widgets Board. This gives you more space for your favorite widgets and helps you stay informed with a feed that connects you to current events. A new navigation bar on the left side makes it easy to switch between your widget’s dashboard and other views like the Discover feed. After initial launch in the EEA, these updates are expanding to all regions. New! A new visual experience is available for the Discover feed on the Widgets Board. The layout is more organized, personalized, and engaging. Copilot-curated stories are now included, offering a well-rounded view of each topic with summaries, videos, and images from trusted MSN premium publishers. To customize your feed, go to Widgets > Discover dashboard > Personalization settings.[Windows Backup for Organizations]New! Windows Backup for Organizations is now generally available! Experience seamless device transitions with enterprise-grade backup and restore. Whether you're refreshing your organization’s devices, upgrading to Windows 11, or deploying AI-powered PCs, this solution helps sustain productivity with minimal disruption, ensuring business continuity and organizational resilience.[PowerShell 2.0] Starting in August 2025, Windows 11, version 24H2, will no longer include Windows PowerShell 2.0. This legacy component was introduced in Windows 7 and officially deprecated in 2017. Most users won’t be affected, as newer versions such as PowerShell 5.1 and PowerShell 7.x remain available and supported. If you use older scripts or tools that depend on PowerShell 2.0, update them to avoid compatibility issues.[Live captions] Fixed: Changing the opacity of live captions in Settings > Accessibility > Captions > Caption Style, has no effect.[Input] Fixed: Attempting to type Chinese with an IME after copying something with CTRL + C can result in the first character not displaying.Fixed: An underlying issue related to textinputframework.dll could result in certain apps like Sticky Notes and Notepad crashing.[dbgcore.dll] Fixed: An underlying issue with dbgcore.dll could result in certain apps, including explorer.exe, crashing.[Kerberos] Fixed: There might be an underlying crash in Kerberos when attempting to access a cloud file share.[Login] Improved: Addressed some underlying cases which could lead to you seeing a blank white screen, or a screen saying, "just a moment", for a few minutes when logging into your PC.[Miracast] Fixed: An issue where, on certain devices, audio would initially play but stop a few seconds after casting to a TV.[Audio] Improved: Addressed an underlying audio service stops responding which could impact the ability to play audio in certain cases.改良と修正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.[Device management] Fixed: This update addresses an issue that prevented some system recovery features from working properly due to a temporary file sharing conflict. This affected certain device management tools and disrupted key functions on some devices.[File system] Fixed: An issue in Resilient File System (ReFS) where using backup apps with large files could sometimes exhaust system memory.[Input] Fixed: This update addresses an issue with the Chinese (Simplified) Input Method Editor (IME) where some extended characters appear as empty boxes.[Fixed This update addresses an issue that prevents typing on the touch keyboard when using the Microsoft Changjie, Microsoft Bopomofo, or Microsoft Japanese Input Method Editors (IMEs). The issue occurs after switching to a previous version of the IME.[Performance] Fixed: This update addresses an issue that slows application installation on ARM64 devices. Some installers might take longer to complete.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以下の2件の既知の不具合が存在します。Error events are logged for CertificateServicesClientSymptomsAfter installing the July 2025 Windows non-security preview update (KB5062600) or a later update, including the August 2025 Windows security update, you might see the following error in Event Viewer related to CertificateServicesClient (CertEnroll): The "Microsoft Pluton Cryptographic Provider" provider was not loaded because initialization failed. This event appears with Error ID 57 and is logged every time the device restarts. It does not indicate a problem with any active Windows component. The event is related to a feature that is currently in development.There is no impact to Windows functionality, and no action is required.WorkaroundA resolution is expected soon. Additional details will be provided as they become available.Network Device Interface streaming performance issueSymptomsAfter installing the August 2025 Windows security update (KB5063878), you might experience delays or uneven audio and video performance when using Network Device Interface (NDI) to stream or transfer feeds between PCs.This issue affects streaming apps such as OBS Studio (Open Broadcaster Software) and NDI Tools, especially when Display Capture is enabled on the source PC. The problem can even occur under low-bandwidth conditions.WorkaroundTo work around the issue, NDI recommends manually changing the NDI Receive Mode to use TCP or UDP instead of RUDP. For steps to do this, see the NDI support site: Traffic Drops After Windows Update.The issue is under investigation, and additional information will be shared as soon as it becomes available.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。