24H2/23H2からWindows 11 25H2に安全にアップグレードする方法

2025年10月15日
24H2/23H2からWindows 11 25H2に安全にアップグレードする方法

If you plan to Windows 11 25H2へのアップグレード, choosing the correct installation method matters. Windows 11 24H2 users can usually complete the update quickly, while Windows 11 23H2 and Windows 10 users may need a full feature upgrade. In addition, some eligible PCs may not see the update immediately in Windows Update.

このガイドでは、以下の方法を説明します。 Windows 11 25H2へのアップグレード safely with Windows Update, the Windows 11 Installation Assistant, an ISO file, or the KB5054156 enablement package. You will also learn how to fix a Windows 11 25H2 not showing problem and protect your files before upgrading.

Although Windows upgrades normally keep personal files, problems such as interrupted installations, accidental clean installs, or partition changes can still cause data loss. Therefore, back up important files first. If files disappear after the update and no backup is available, Magic Data Recovery provides another HDDデータ復旧 オプションがある。.

Magic Data Recoveryをダウンロード

Windows 7/8/10/11およびWindows Serverをサポート

目次

Should You Upgrade to Windows 11 25H2 in 2026?

For most eligible PCs still running Windows 11 24H2, it makes sense to Windows 11 25H2へのアップグレード.

Microsoft released Windows 11 25H2 on September 30, 2025. Windows 11 24H2 Home and Pro editions reach the end of updates on October 13, 2026, while Windows 11 25H2 Home and Pro remain supported until October 12, 2027. Therefore, moving from 24H2 to 25H2 extends the supported lifecycle of your PC.

You may also see Windows 11 26H1 on Microsoft’s release information page. However, Microsoft states that 26H1 targets new devices released in 2026 and does not serve as an in-place feature update for existing 24H2 or 25H2 PCs. Consequently, existing users should not assume they need to skip 25H2 and move directly to 26H1.

For Windows 11 24H2 users, the Windows 11 24H2 to 25H2 transition is especially straightforward because both versions share the same core system files. Microsoft uses an enablement package to activate the 25H2 features already present in an updated 24H2 installation.

Before You Upgrade to Windows 11 25H2

その前に Windows 11 25H2へのアップグレード, spend a few minutes checking your PC. These precautions reduce the risk of compatibility problems and data loss.

Check Windows 11 Compatibility

If your PC already runs Windows 11 24H2, it normally meets the basic Windows 11 requirements. However, Windows 10 users should confirm compatibility before starting the upgrade.

Microsoft requires supported hardware, including a compatible 64-bit processor, TPM 2.0, Secure Boot capability, sufficient storage, and other Windows 11 requirements.

Avoid forcing Windows 11 onto unsupported hardware simply because an ISO workaround exists. Microsoft warns that unsupported PCs may experience compatibility problems and may not qualify for updates.

Install Pending Updates

Next, open:

[設定] > [Windows Update] > [更新プログラムの確認]

Install available cumulative updates before starting the feature upgrade. This step matters especially when using the Windows 11 25H2 enablement package, because KB5054156 requires Windows 11 24H2 with the necessary cumulative update level.

Update Important Drivers

Also check your PC manufacturer’s support page for recent storage, chipset, graphics, Wi-Fi, and BIOS or firmware updates.

You do not need to update every driver manually. However, if the manufacturer specifically recommends a driver or firmware update for newer Windows versions, installing it first may prevent compatibility problems.

Back Up Important Files

その前に Windows 11 25H2へのアップグレード, copy important documents, photos, work files, and other irreplaceable data to another drive or backup service.

An in-place upgrade usually keeps your personal data. Nevertheless, a backup protects you from unexpected shutdowns, installation failures, accidental formatting, or choosing the wrong installation option.

How to Upgrade to Windows 11 25H2: 4 Safe Methods

There is no single best method for every PC. Instead, choose a method based on your current Windows version and whether Windows Update already offers 25H2.

Method 1: Upgrade to Windows 11 25H2 via Windows Update

Windows Update is the easiest and safest method for most users.

If you currently run Windows 11 24H2, start here.

  1. プレス ウィンドウズ＋I to open Settings.
  2. 選択 ウィンドウズ・アップデート.
  3. クリック アップデートの確認.
  4. 探す Windows 11, version 25H2.
  5. クリック ダウンロードとインストール if Windows offers the update.
  6. Allow Windows to complete the installation.
  7. Restart the PC when prompted.

Microsoft states that eligible unmanaged Windows 11 24H2 Home and Pro devices can receive 25H2 through Windows Update.

For most 24H2 PCs, this is the preferred way to Windows 11 25H2へのアップグレード because Windows Update checks device compatibility before offering the feature update.

コンピューターをWindows 10から最新バージョンのOSにアップグレードするには

Method 2: Upgrade with Windows 11 Installation Assistant

If Windows Update does not offer 25H2 even though your PC meets the requirements, the official Windows 11 Installation Assistant provides another solution.

This method can also help users moving from an older supported Windows release.

  1. Visit Microsoft’s official Download Windows 11 ページ。.
  2. 探す Windows 11 Installation Assistant.
  3. 選択 今すぐダウンロード.
  4. Run the downloaded tool as an administrator.
  5. Allow the assistant to check your hardware.
  6. Accept the license terms and select Accept and Install.
  7. Wait while Windows downloads and prepares the update.
  8. 選択 Restart Now プロンプトが表示されたら.

Microsoft currently describes Installation Assistant as the best option for installing Windows 11 on the PC you are using. It requires an x64 processor and does not support Arm-based PCs.

したがって、もし～する必要がある場合は、 Windows 11 25H2へのアップグレード but Windows Update does not offer it, Installation Assistant is usually the next method to try.

Method 3: Upgrade to Windows 11 25H2 Using an ISO

An official Windows 11 ISO gives you more control and works well when Windows Update fails or when you want to perform an in-place upgrade manually.

へ Windows 11 25H2へのアップグレード without intentionally removing your personal files:

  1. Download the current Windows 11 ISO from Microsoft’s official download page.
  2. Locate the ISO file in File Explorer.
  3. 右クリックして Mount.
  4. Open the mounted virtual drive.
  5. 走る setup.exe.
  6. Follow the Windows Setup instructions.
  7. When prompted, choose the option to keep personal files and apps.
  8. Continue the installation and allow the PC to restart.

Microsoft confirms that mounting an ISO and running Setup can upgrade the current operating system to Windows 11.

Be careful here. Booting directly from installation media can lead you toward a clean installation instead. If your goal is an in-place upgrade, start setup.exe from inside your current Windows installation and verify the option that preserves your apps and personal files.

Method 4: Upgrade Windows 11 24H2 to 25H2 with KB5054156

For users already running Windows 11 24H2, KB5054156 provides a particularly efficient upgrade path.

Windows 11 24H2 and 25H2 use the same core operating system and system files. Therefore, Microsoft can activate 25H2 through a small Windows 11 25H2 enablement package rather than reinstalling the entire operating system.

In most cases, Windows Update handles the package automatically. After installation, one restart activates version 25H2.

However, remember this important limitation:

KB5054156 is for Windows 11 24H2 devices.

Do not treat the enablement package as a universal upgrade file for Windows 10, Windows 11 23H2, or much older releases. Those systems may require a full feature upgrade instead.

コンピュータをWindows 11から最新バージョンのオペレーティングシステムにアップグレードする。

Windows 11 25H2 Not Showing? Try These Fixes

Sometimes you may want to Windows 11 25H2へのアップグレード, but Windows Update does not display it.

First, do not immediately download unofficial installation files. Instead, work through these checks.

Install All Pending Windows Updates

Open Windows Update and install any pending quality, servicing, or cumulative updates. Then restart the PC and check again.

For 24H2 devices, keeping the system current also helps satisfy the prerequisites for the 25H2 enablement package.

Check Hardware Compatibility

Windows Update may withhold a feature upgrade from hardware that does not meet Windows 11 requirements.

Windows 10 users should pay particular attention to TPM 2.0, Secure Boot, processor support, and storage requirements.

Restart and Check Again

A pending restart can interfere with update detection. Therefore, restart Windows before checking for 25H2 again.

Then go to:

[設定] > [Windows Update] > [更新プログラムの確認]

Check for a Safeguard Hold

Microsoft sometimes applies a safeguard hold when it identifies a compatibility problem with specific hardware, drivers, or software. The hold temporarily prevents Windows Update from offering the new Windows version to affected devices.

Microsoft recommends allowing the hold to remain until it resolves the underlying issue.

Therefore, do not automatically force upgrade Windows 11 25H2 when Windows reports that the update is not ready for your device.

Use Installation Assistant or an ISO

If the PC meets all requirements and no known compatibility issue applies, you can consider Microsoft’s Installation Assistant or official ISO.

However, check the Windows Release Health page first. This simple step can prevent you from installing an update on a device affected by a known problem.

アップグレード中にデータが失われる一般的なシナリオ

準備をしていても、うまくいかないことはある：

停電によるアップグレード中断

インプレースアップグレードの代わりにクリーンインストール

ISOインストール中にフォーマットされたパーティション

アップデート後にユーザーファイルが見つからない

バックアップをスキップした場合、ファイルは失われたように見えるかもしれないが、復旧は可能だ。.

What If Files Are Missing After the Windows 11 25H2 Upgrade?

アップグレード後、ファイルが消えた場合、, Magic Data Recovery Windowsアップグレード後 が解である。.

Magic Data Recoveryを選ぶ理由

Windowsのアップグレード中に失われたファイルを復元

NTFS、FAT、exFATファイルシステムをサポート

写真、ドキュメント、ビデオ、アーカイブの復元

使いやすいディープスキャン・オプション

紛失したファイルを復元する手順

1. ダウンロード＆インストール:取得 Magic Data Recovery を公式ウェブサイトからダウンロードし、コンピュータにインストールしてください。.

Magic Data Recoveryをダウンロード

Windows 7/8/10/11およびWindows Serverをサポート

2.ドライブを選択します。:ソフトウェアを起動し、ファイルを紛失したドライブを選択します。.
Magic Data Recoveryを実行し、失われた上書きファイルを検索する。
3.スキャンを開始する:紛失したデータの検索」をクリックしてください。まずクイックスキャンを開始し、次にディープスキャンを開始します。.
失われたデータの検索
4.プレビューと選択:スキャン後に検出されたファイルをブラウズしてプレビューします。.
Windows 11 25H2へのアップグレードに失敗し、ファイルを紛失した。
5.回復:必要なファイルを選択して 別ドライブ (紛失したファイルではありません）。.
回復した上書きファイルを保存する
Magic Data Recoveryの使用手順については、ビデオもご覧ください。.

まとめ

For most eligible users, the best way to Windows 11 25H2へのアップグレード is to start with Windows Update. Windows 11 24H2 users benefit from the lightweight KB5054156 enablement package, while Installation Assistant and an official ISO provide useful alternatives when the normal update path does not work.

Before upgrading, install pending updates, check compatibility, and back up important data. Moreover, avoid forcing the update when Microsoft has placed a safeguard hold on your device.

If an upgrade failure, accidental clean installation, or partition mistake causes files to disappear, Magic Data Recovery provides a practical recovery option because it scans for lost files rather than trying to repair Windows itself. Still, ハードドライブ・データ復元 works best before new data overwrites the missing files.

Magic Data Recoveryをダウンロード

Windows 7/8/10/11およびWindows Serverをサポート

よくあるご質問

Windows 11 23H2から25H2に直接アップグレードできますか？

Yes, an eligible PC can move from an older Windows 11 release to 25H2 through an available Microsoft upgrade path. However, the lightweight KB5054156 enablement package applies specifically to Windows 11 24H2. Therefore, a 23H2 PC may need a full feature upgrade through Windows Update, Installation Assistant, or official installation media.

Should I upgrade Windows 11 24H2 to 25H2?

For most Home and Pro users, yes. Microsoft lists October 13, 2026 as the end-of-updates date for Windows 11 24H2, while 25H2 remains supported until October 12, 2027. In addition, the shared core between these versions makes the Windows 11 24H2 to 25H2 upgrade relatively lightweight through the enablement package.

Why is Windows 11 25H2 not showing in Windows Update?

A Windows 11 25H2 not showing issue can result from pending updates, hardware compatibility, managed update policies, or a Microsoft safeguard hold. First install pending updates and restart the PC. Next, check Microsoft's Windows Release Health information. If your PC remains eligible and has no known block, consider Installation Assistant or an official ISO.

What is the Windows 11 25H2 enablement package KB5054156?

KB5054156 is the official Windows 11 25H2 enablement package for devices running Windows 11 24H2. Because 24H2 and 25H2 share the same core operating system files, the package acts like a switch that activates 25H2 features already present on an updated 24H2 installation. It requires a restart after installation.

Can I upgrade Windows 10 directly to Windows 11 25H2?

An eligible Windows 10 PC can use Microsoft's Windows 11 upgrade tools if it meets Windows 11 hardware requirements. Installation Assistant requires Windows 10 version 2004 or later, among other conditions. Before you upgrade to Windows 11 25H2, use Microsoft's compatibility guidance and back up important files instead of bypassing unsupported hardware requirements.

Is it safe to force upgrade Windows 11 25H2 with an ISO?

An official ISO can provide a safe in-place upgrade path for a compatible PC. However, you should not use it simply to bypass a safeguard hold. Microsoft creates safeguard holds when known compatibility problems could affect specific devices. Therefore, check Release Health first and use only official Microsoft installation media when you need to upgrade to Windows 11 25H2 manually.

エリン・スミスは、Amagicsoftで最もプロフェッショナルなライターの一人として認められています。過去10年にわたりライティングスキルを磨き続け、何百万人もの読者の技術的な問題解決に貢献してきました。.