This error indicates that the installation failed in the SECOND_BOOT phase during the SYSPREP_RESPECIALIZE operation, suggesting a failure in reconfiguring the system during the setup process. The most common cause is incompatible or outdated drivers, particularly those related to storage devices, network adapters, or USB controllers. Additional factors include outdated BIOS firmware, connected external peripherals, antivirus software interference, or corrupted system files. Now that you’re familiar with the main causes of the 0xC19001-0x40021 error, let’s explore several proven methods used by other users to overcome this issue and successfully upgrade to Windows 11.
1. Check if the Hardware is Compatible with Windows 11
Due to Windows 11’s stringent requirements, it is crucial to verify if your system supports the new operating system before troubleshooting further. Microsoft has introduced mandatory requirements such as TPM 2.0 and Secure Boot, along with other hardware standards. If you are uncertain about your PC’s compatibility, you can use Microsoft’s PC Health Check app to confirm whether your computer meets the minimum requirements. Note: The PC Health Check app, after initial inaccuracies in reporting, has since been updated by Microsoft and is now reliable.
2. Run the Windows Update Troubleshooter
Once you have verified compatibility, the next step is to check if a Windows Update component is preventing the upgrade. Various issues can impact Windows Update. The Windows Update Troubleshooter automatically detects and repairs many of these common problems. It is equipped with automated repair strategies that address scenarios known to hinder Windows updates, including OS upgrades.
3. Reset All Windows Update Components
If the troubleshooter did not resolve the issue, there may still be underlying corruption affecting the Windows Update components. To thoroughly address possible corruption, you should reset Windows Update components and all related dependencies. Additionally, clear both the Catroot2 and SoftwareDistribution folders, as they store update files and can sometimes become corrupted.
4. Run SFC, DISM, and CHKDSK Scans
If resetting Windows Update does not resolve your issue, your system may have deeper corruption affecting files or storage sectors. Windows provides built-in utilities to detect and repair such damage: SFC (System File Checker), DISM (Deployment Image Servicing and Management), and CHKDSK (Check Disk). Each tool addresses different aspects of system integrity:
SFC repairs corrupted or missing system files using locally cached data.DISM restores the system image by downloading healthy components from Microsoft servers.CHKDSK checks for and fixes disk errors.
5. Downgrade to an Older Windows 10 Build (If Applicable)
If previous solutions have not worked and you are running an Insider or unsupported version of Windows 10, the upgrade may be blocked. Some users have discovered that downgrading to an earlier, stable version of Windows 10 (such as 20H2 or builds released before March 20, 2021) enables the Windows 11 upgrade to proceed without errors.
6. Uninstall ASUS Xonar Driver Prior to Upgrading (If Applicable)
If you have ASUS hardware, the ASUS Xonar sound driver is reported to interfere with the Windows 11 upgrade process, causing the 0xC19001-0x40021 error. Removing this driver through Device Manager often resolves the issue.
7. Disable DRM Software That Interferes with the Windows 11 Upgrade (If Applicable)
A known upgrade blocker is the legacy DRM software, Aladdin Knowledge Systems, which can conflict with the Upgrade Assistant. If this module is present, it serves no practical purpose for modern systems and can be safely disabled.
8. Temporarily Disable Antivirus or Security Software (If Applicable)
Third-party antivirus or firewall programs are another common reason why upgrades to Windows 11 fail, especially suites like Zone Alarm. These applications may block or interfere with the upgrade installer by restricting file or registry access. To check whether your antivirus is responsible, disable its real-time protection temporarily before starting the upgrade process. Note: Most antivirus programs allow you to disable real-time protection from their system tray icon or within their settings. If not, you can consider uninstalling the security suite completely, especially if it also functions as a firewall.
9. Remove Secondary SSDs and External Devices (If Applicable)
Another documented cause of the 0xC19001-0x40021 error is the presence of additional drives or peripherals during the upgrade process. Although the exact reason is unclear, disconnecting any unnecessary external or internal SSDs, HDDs, and non-essential USB devices has helped many users complete the upgrade. To do this, unplug all devices not needed for basic PC operation. If you have a secondary or data-only internal drive, consider disconnecting it physically by removing its data or power cable. After disconnecting non-essential devices, retry the Windows 11 upgrade.
