Accessing Windows network shares and UNC paths

Magnus Box can back up Windows network paths, and back up to Windows network storage (SMB / CIFS). However, because Magnus Box runs as a service user, there are some issues with authentication to be aware of.

Please note that if you are using Magnus Box to back up data from a network device, you should prefer to install Magnus Box directly on the device instead of backing it up over the network. This will also significantly improve performance, as less data needs to be transferred over the LAN.

Mapped network drives

On Windows, each logged-on user session has its own set of mapped network drives. The service user account is unlikely to have any mapped drives. If you see error messages like WARNING Missing: 'Z:\', this is probably the reason. You can work around this by using a UNC path instead.

The Magnus Box desktop application will automatically convert mapped network drives to their UNC path equivalents.


If the UNC share requires authentication, the service user account is probably not logged-in to the UNC share. If you see error messages like WARNING Lstat: CreateFile \\?\UNC\...: Access is denied., this is probably the reason.

Magnus Box 18.6.5 and later have built-in options for setting Windows network authentication credentials.

For versions of Magnus Box prior to 18.6.5, workarounds are available ranked in order of preference:

  • If you are using Magnus Box to store data on a network device, you may be able to install Magnus Box on the network device. If the network device is a NAS box (e.g. Synology / QNAP), Magnus Box can be installed on Linux x86_64 NAS boxes.
  • In Magnus Box, you can work around this issue by adding net use \\HOST\SHARE /user:USERNAME PASSWORD as a "Before" command to the backup job.
    - If you are storing data on a UNC path, you can add this "Before" command on the Storage Vault instead of on the Protected Item. This will ensure it is run for all backup jobs going to that Storage Vault.
  • You can work around this issue in Magnus Box by changing the Windows Service to use a different user account.
    - This is the Magnus Box (delegate service) service.
    - If you are using Magnus Box on a Windows Server machine that is acting as the Domain Controller, you must choose a domain account.
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