SIRIS, ALTO, and NAS: Boot error, "The operating system couldn’t be loaded because the digital signature of a file couldn’t be verified," after system restore



After performing a restore such as a Bare Metal Restore (BMR), or image export, the restored server encounters a winload error referencing \Windows\System32\Drivers\viostor.sys. The error presented is often, “The operating system couldn’t be loaded because the digital signature of a file couldn’t be verified”, with a status of 0xc0000428.


  • Datto SIRIS
  • Datto ALTO
  • Microsoft Windows


The driver viostor.sys (used by Datto as a standardized interface for drive management) conflicts with certain hardware environments running Windows.

figure1.pngFigure 1: Winload error (click to enlarge)


1. Press Enter followed by F8 to load the Advanced Boot Options screen.

2. Select Disable Driver Signature Enforcement and press Enter.

figure2.pngFigure 2: Advanced Boot Options (click to enlarge)

If you need to disable the driver permanently to ensure reboots are successful, or you are receiving a different winload error referencing viostor.sys, follow the steps below.

Edit the registry

Once the OS loads, open the Windows Registry Editor and navigate to HKEY_LOCAL_MACHINE → SYSTEM → CurrentControlSet→ Services → Viostor.  Double-click the Start parameter and set the Value data to 4, then click OK.

figure3.pngFigure 3: Registry Editor (click to enlarge)

Offline systems

If you are editing the registry from an offline system, such as the Windows Recovery Environment or an install ISO, you will first need to load the offline registry hive by clicking File → Load Hive.

figure4.pngFigure 4: Load Hive (click to enlarge)

Once you've made the changes in the registry, click File → Unload Hive.

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