What’s New in Excel August 2026: Change History + KB5120248

WINDOWS AI NEWSAug 26, 20269 min read

Quick Answer

Excel’s August 2026 update adds Change History for workbooks plus Python in Excel – what shipped, how to use it, and what it means for your spreadsheets.

KeyStarter Editorial Team

AI-assisted research & drafting, editorially reviewed

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Quick answer – what is KB5120248? It is Microsoft’s August 2026 Dynamic Update for Windows 10 version 21H2 (Safe OS / setup dynamic update, published to the Microsoft Update Catalog on August 11, 2026). It ships automatically through Windows Update during upgrade or repair installs and is safe to install. If a repair install broke your activation, see our Windows activation failure fixes; if you are preparing Windows 10 for ESU coverage, the ESU enrollment guide walks through the prerequisites.

01Excel Copilot Adds Change History and Chat History

The August 2026 Excel update, published on August 25, adds a Copilot change history skill, Copilot chat history, chart and PivotTable skills, and a Python skill for Insiders. The change history skill is the standout: Copilot can summarize how a workbook has evolved, identify who made edits, explain how both people and AI changed it, and help undo specific edits or restore formulas by returning the workbook to a previous working state.

Chat history lives in the upper-left menu of the Copilot pane, with conversations listed by recency, and access requires a Microsoft 365 Copilot commercial license. The chart and PivotTable skills let users summon @chart-design to improve visualizations and create organized PivotTables to summarize data, while the Python skill (@python-in-excel) targets Insiders who want editable, refreshable Python formulas in the workbook. Microsoft labels all four as Feedback in Action features driven by user requests.

There is also a cleanup note worth flagging: Microsoft is retiring the =COPILOT worksheet function on September 14, 2026, after roughly a year of preview, because the Copilot pane already covers the same ground. Workbooks that rely on =COPILOT formulas will stop creating new ones after that date, so finance and operations teams should migrate to the pane now. For everyday users, the change history skill is the most immediately useful addition – it turns Excel’s revision story into something you can actually ask questions about.

02Windows on Arm Crosses 7,000 Verified Apps

Microsoft’s App Assure team reports that the Works on Windows on Arm catalog now lists more than 7,000 verified apps and games, and NVIDIA’s RTX Spark SoC will join the platform this fall with devices from Microsoft Surface, ASUS, Dell, HP, Lenovo, and MSI. The Windows Developer Blog published the update, ‘Expanding the Windows on Arm app ecosystem across key workloads,’ on August 25, framing the milestone as proof that Windows on Arm has become a first-class platform for any workload.

The progress report covers four workload categories. STEM and education apps are growing fastest as classrooms and research environments adopt Arm devices; security additions build on earlier work from Norton, CrowdStrike, and McAfee in endpoint protection and Nord, Zscaler, and Palo Alto Networks in VPN and Zero Trust; productivity additions join established names like Google, Adobe, Slack, Trello, and Dropbox; and creativity additions follow Camtasia, Blender, and Figma. The catalog is built with compatibility data supplied by Microsoft, and App Assure’s Arm Advisory Service continues to help developers close gaps.

For buyers, the practical question is shifting from whether apps exist to whether the specific drivers, plug-ins, and line-of-business tools your team needs are native Arm64 builds. The 7,000-app catalog makes Arm laptops credible for everyday and professional use, and NVIDIA’s entry gives the platform a second silicon supplier alongside Qualcomm. If you are evaluating an Arm Copilot+ PC, our Windows 11 Pro vs Home guide covers the edition decisions that matter first.

03Server vNext 29651 Previews Trusted Launch

Windows Server 2025 LTSC vNext Preview build 29651, released on August 24, introduces Trusted Launch for virtual machines, Quick Machine Recovery, an NVMe-oF initiator, and ReFS boot support. The preview includes both Desktop Experience and Server Core options for Datacenter and Standard editions, plus an Azure Edition for VM evaluation only.

Trusted Launch is the headline feature: the initial preview supports VMs with Secure Boot, vTPM, and vTPM state protection at rest, all managed through PowerShell. Microsoft is explicit about preview limits – moving TVMs between servers is not supported yet, and neither are TVMs in failover clusters or Hyper-V Replica, nor Trusted Launch management in Windows Admin Center. The same build also enables Quick Machine Recovery for Server Insiders as part of the Windows Resiliency Initiative, ships an NVMe-over-Fabrics initiator supporting both TCP and RDMA, and turns on ReFS boot – with a known 2 GB WinRE partition limitation to plan around.

Enterprise testers should note the baseline rules: clean install from build 29531 or later is required, upgrades from builds older than 29531 are not supported, and this LTSC preview expires on October 15, 2027. The TLS hybrid key exchange known issue is worth checking too – administrators may need to disable hybrid groups until the fix lands. For IT teams that run a large virtualized estate, Trusted Launch previews the kind of hardware-backed isolation that will likely become standard in the next Server LTSC.

04Visual Studio Sharpens Copilot and Git Workflows

Visual Studio 2026’s August update, published on August 25, lets developers set Copilot thinking effort to Low, Medium, or High, share custom agents at the organization level, and manage Git worktrees and submodules from the IDE. The thinking-effort control is available for supported models from the Model picker or the expanded Language Models view, so teams can trade response depth against speed and token usage per task.

Organization-level agents are the productivity win: GitHub organization and enterprise owners can publish custom agents that everyone in the organization can use across repositories, and Visual Studio detects them automatically when you work in an eligible repository. A new Copilot usage panel, reachable from the prompt box context window, shows how much of the plan has been used with more actionable notifications near the limit. On the Git side, worktrees give each branch its own working directory so changes stay in place while you switch tasks, and submodules get a dedicated section with add, update, and delete operations – read-only by default until you opt in via Tools > Options > Source Control > Git.

This is a quiet release that answers loud requests: token-conscious developers get explicit control over model reasoning, platform teams get consistent agent behavior across repos, and anyone who juggles branches gets worktrees without leaving the IDE. None of these require migration, but they do change how Copilot plans and Git repositories behave, so teams should document the new defaults before rollout.

05One Copilot App: Consumer and M365 Merge

Microsoft has unified its consumer Copilot app and Microsoft 365 Copilot into a single Microsoft Copilot app, with the migration beginning on August 18. The Verge reported the merger on August 12, and Microsoft’s own deployment documentation confirms that the Microsoft 365 Copilot app is now called Microsoft Copilot, with an updated name and icon.

The unified app combines chat and image creation with direct access to Word, Excel, Outlook, and other Microsoft 365 apps, files, and content, and supports personal, work, and school accounts in one place with data logically separated. Users can connect email, calendar, and cloud storage so Copilot has context across work and home. As part of the consolidation, a few preview features were retired – TechRepublic lists the disappearing capabilities alongside the August 18 migration date, and Microsoft Learn now documents deployment for IT teams rolling out the unified application.

For users, the practical effect is one app to install and one sign-in flow instead of a confusing consumer-versus-work split. For IT, the consolidation simplifies licensing conversations but raises policy questions: the same app now handles personal and work identities, so conditional access and data boundaries matter more than before. The unified app is also the first step toward the larger Copilot super app Microsoft has signaled for later this year.

06AFD.sys Zero-Day: BOD 26-04 Deadline Passes

CVE-2026-68820, a use-after-free in the afd.sys driver exploited by North Korea’s Lazarus group, was patched and added to CISA’s Known Exploited Vulnerabilities catalog on August 11 – and its BOD 26-04 remediation deadline passed on August 25. Qualys explained the timeline on August 18: publicly exposed systems faced a three-day deadline (August 14) and internal endpoints a 14-day deadline (August 25).

The vulnerability lives in the Windows Ancillary Function Driver for WinSock, which sits on every Windows endpoint and is reachable from any low-privilege account. An attacker with a foothold runs a crafted application, wins the race, and escalates to SYSTEM with no user interaction. Security researchers attribute active exploitation to the Lazarus group’s Operation Dream Job campaign against defense contractors, with Check Point flagging the attack chain. The fix ships in the August cumulative update – KB5121003 for Windows 11 and KB5120249 for Windows 10 under Extended Security Updates – and Microsoft identifies no workaround.

The trap for IT teams is the reboot. Because the fix replaces a kernel driver, the vulnerable driver remains loaded and active until the endpoint restarts, so a patched-but-not-rebooted machine is still exposed. With both BOD 26-04 deadlines now passed, organizations that have not verified remediation should treat the exposure as unresolved and confirm reboot completion on every affected endpoint – particularly any system that has not been restarted since the August update was installed.

07What This Means for Windows Users and IT Teams

The week’s Windows and Microsoft AI news boils down to three practical takeaways: Arm hardware is now a credible mainstream option, the August security patch only counts once endpoints reboot, and Microsoft is consolidating Copilot – in Excel, in Visual Studio, and in a single unified app. None of these require emergency action today, but several have deadlines or rollout windows already in motion.

For Windows users: if you bought or are evaluating an Arm Copilot+ PC, check the Works on Windows on Arm catalog for your specific apps before switching; if you use Excel, the change history skill is worth enabling and the =COPILOT retirement on September 14 needs a plan; and if your PC has the August update installed but has not rebooted since, restart it to complete the AFD.sys fix. When you are ready to move, our Best Windows License Buying Guide 2026 explains how to buy Windows 11 Pro safely.

For IT teams: verify reboot completion for KB5121003 and KB5120249 before closing the KEV ticket; start a Server vNext 29651 evaluation if Trusted Launch matters to your virtualization roadmap; document the unified Microsoft Copilot app for conditional access; and check whether your dev teams want organization-level Copilot agents and worktree support in Visual Studio. For fleets comparing editions, the Windows 10 vs Windows 11 guide is a useful starting point.

The through-line is consolidation with discipline: Microsoft is unifying Copilot surfaces while hardening the platform underneath, and the deadlines that matter – the =COPILOT retirement, the KEV remediation dates, and the fall Arm device wave – are all within the next few weeks.

FAQ

External References

• • Windows Developer Blog: Expanding the Windows on Arm app ecosystem across key workloads (Aug 25, 2026)
• • Microsoft Community Hub: Announcing Windows Server vNext Preview Build 29651 (Aug 24, 2026)
• • Microsoft Community Hub: Announcing Trusted Launch for Virtual Machines for Windows Server Insiders
• • Microsoft Excel Blog: What’s New in Excel August 2026 (Aug 25, 2026)
• • Visual Studio Blog: Visual Studio August Update – Work Smarter Across Models and Branches (Aug 25, 2026)
• • CISA: CISA Adds Three Known Exploited Vulnerabilities to Catalog (Aug 11, 2026)
• • Qualys: CVE-2026-68820 Is in KEV. What BOD 26-04 Requires Now (Aug 18, 2026)
• • SC Media: DPRK’s Lazarus Group exploits Windows zero-day in backdoor campaign (Aug 13, 2026)
• • Security Affairs: North Korean Lazarus Group uses Windows zero-day in Operation Dream Job (Aug 12, 2026)
• • The Verge: Microsoft is combining its Copilot apps ahead of a ‘super app’ (Aug 12, 2026)
• • Microsoft Learn: Deploy the unified Microsoft Copilot application (updated Aug 17, 2026)
• • TechRepublic: Microsoft Merges Copilot Apps as Features Disappear Starting Aug. 18 (Aug 14, 2026)
• • Impress Watch: Microsoft 365 Copilot app becomes the unified Microsoft Copilot app (Aug 25, 2026)
• • 4sysops: Windows on Arm passes 7,000 apps as NVIDIA RTX Spark joins the platform (Aug 24, 2026)
• • The Register: Excel’s Copilot function is headed for the Recycle Bin (Aug 17, 2026)

By KeyStarter Editorial Team
This article was compiled with AI assistance for research and drafting and has been editorially reviewed. All sources are listed above.

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