Windows 10 21H2 無料認証方法 2026 — ステップバイステップ

KMSAuto software walkthrough

Run the steps below in order — the full KMSAuto download flow takes roughly 90 seconds from extract to licensed.

• Temporarily disable Defender real-time protection (Windows Security → Virus & threat protection → Manage settings)
• Unpack the KMSAuto download with the password shown beside the download button on kmsauto.software
• Right-click KMSAuto.exe and pick 'Run as administrator' — UAC elevation is required
• Inside the KMSAuto software window, pick HWID for Windows or Ohook for Office (TSforge for LTSC / 24H2)
• Wait for the green 'Successfully activated' banner, then reboot once to finalize the license

Verifying the license

Open an elevated Command Prompt and run `slmgr /xpr` for Windows or `cscript ospp.vbs /dstatus` from the Office install folder. KMSAuto software targets a permanent digital license where possible and falls back to a 180-day renewing KMS lease on editions that do not support HWID.

Windows 10 21H2 System Requirements & Compatibility (2026)

Windows 10 21H2 is engineered for the modern Microsoft activation stack. The tool runs on Windows 7 SP1, Windows 8.1, Windows 10 (all builds from 1507 to 22H2) and every Windows 11 release including 23H2 and 24H2. Both x64 and ARM64 hardware are supported, and the activator also recognises Server SKUs such as Server 2016, 2019 and 2022. On the Office side, Click-to-Run installations of Office 2013, 2016, 2019, 2021, 2024 and Microsoft 365 are detected automatically — including LTSC channels. You do not need to uninstall a previous KMS client or remove an existing product key: the script reads the current edition through slmgr and routes it to the correct activation method (HWID for Windows, Ohook for Office).

• Windows 7 SP1 / 8.1 / 10 / 11 — all editions (Home, Pro, Education, Enterprise, IoT, LTSC)
• Windows Server 2008 R2 through Server 2025
• Office 2010, 2013, 2016, 2019, 2021, 2024 and Microsoft 365 Apps
• Architectures: x86, x64, ARM64
• .NET Framework 4.6+ (preinstalled on Windows 8.1 and later)

Windows 10 21H2 Troubleshooting: Common Errors & Fast Fixes

Most Windows 10 21H2 failures fall into three buckets: antivirus interference, missing administrator rights, or a corrupted Software Protection Service. If you see error 0xC004F074 the KMS host could not be contacted — disable Defender real-time scanning for two minutes, then re-run the activator. Error 0xC004C003 means the product key is blocked by Microsoft; switch to the HWID method, which bypasses key validation entirely by binding the licence to your motherboard's hardware ID. Error 0x80070005 (Access Denied) is always a UAC issue — right-click the executable and select "Run as administrator". If activation succeeds but reverts after reboot, open services.msc, set "Software Protection" to Automatic, and restart sppsvc.exe. For Office, run the Office Click-to-Run repair from Settings → Apps → Microsoft 365 → Modify → Quick Repair before retrying Ohook.

• 0xC004F074 — pause antivirus, re-run as administrator
• 0xC004C003 — switch to HWID (no key required)
• 0x80070005 — UAC denied, use "Run as administrator"
• Activation reverts on reboot — set "Software Protection" service to Automatic
• Office not detected — run Quick Repair, then re-run Ohook