SIRIS, ALTO, and NAS: Agent driver is not loaded. Please restart this system and load the driver.



This article lists the cause and possible solution for the Windows backup error, "Agent driver is not loaded. Please restart this system and load the driver."


  • Datto SIRIS
  • Datto ALTO
  • ShadowSnap Agent


  • The STC Driver was not loaded after installation, most commonly as a result of a machine not being rebooted after the ShadowSnap Installation process is executed.
  • It can also indicate that the stcvsm.sys driver was not properly installed.


Follow these steps:

  1. Reboot the production machine, as this will complete the ShadowSnap Installation process.
  2. Repair agent communications with the protected server.

If problem persists post-reboot

  1. Verify that you have the correct versions of ShadowProtect and ShadowSnap. You can check these software versions from the Device Overview page of the appliance GUI.
  2. Make sure that group policy is not preventing the stcvsm driver from being installed.
    • If it did, it will likely show up as an unknown device. You can be sure this unknown device is linked to stcvsm by looking at the hardware ID property. Once you have done this, browse the other properties for possible causes of the issue.
  3. Disable any group policy setting preventing the installation of the driver.

Reinstall the stcvsm driver

Follow these steps to reinstall the stcvsm driver:

1. Download PSExec.exe from
2. Open a Command Prompt window. Browse to the location PsExec was downloaded to.
3. Run the command psexec.exe -hsi cmd.exe. This will open a second Command Prompt window which will be running as the local system.

Figure 1: psexec.exe -hsi cmd.exe

4. From the new Command Prompt window, browse to <Program Dir>\Storagecraft\Shadowprotect\.
5. Run dir to verify that you can see a file called stcinst.exe.
6. Make a copy of that file and rename it to stcinst.exe.bak.
7. From the Command Prompt window, run stcinst.exe –w.

Figure 2: stcinst.exe –w

8. Download the stcinst.exe installer.
9. Extract the contents of the file to a Stcinst folder on the desktop.
10. In the Stcinst folder, you will see x64 and x86 subfolders. Within these subfolders are installation directories for pre and post-Vista operating systems. Choose the installation directory that corresponds with the host operating system you are running the install on.
11. Note the path of the installer that you're trying to use.
12. Go to "Run" and type cmd to open a command window.

13. Change to the directory where the folder is located: cd Desktop\PsTools

14. Run dir to list the contents of the directory.

15. Once in the directory, run the PsExec tool to invoke a new command prompt that runs as the local system user: psexec.exe -hsi cmd.exe

16. In the new command window that opens, cd into the directory of the stcvsm.sys installer you wish to use.

17. To install the driver, use the following syntax: Stcinst.exe Stcvsm.inf

18. Reboot the machine. Attempt another backup.

Snapshot Driver Issues

1. Open 'Add/Remove programs on the target server

2. Right click on 'StorageCraft ShadowProtect' -> Uninstall/Change

3. Select Modify --> Next --> ensure that 'Snapshot Driver' is checked --> Next --> Next.

4. If it's not checked, check it and reboot.

5. Start a backup for the agent.

6. If the backup still fails with the same error, then reboot your server and restart a backup.


1. Remove the software with a higher level uninstaller that takes care of registry keys and leftover files instead of the normal Windows uninstaller.

2. Perform an advanced reinstall of the ShadowSnap software.

3. Attempt another backup, and observe the results.

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