10090: Acronis Product Does Not Back Up Disks Mapped via Subst

Acronis products currently do not support backing up of locally mapped disks using the subst utility

This article applies to:

  • Acronis Backup & Recovery 10 Advanced Server
  • Acronis Backup & Recovery 10 Server for Windows (Standalone)
  • Acronis Backup & Recovery 10 Advanced Server - Small Business Server Edition
  • Acronis Backup & Recovery 10 Advanced Workstation
  • Acronis Backup & Recovery 10 Workstation (Standalone)
  • Acronis Backup & Recovery 10 Advanced Server - Virtual Edition
  • Acronis True Image Home 2010
  • Acronis True Image Home 2011
  • Acronis Backup and Security 2010
  • Acronis True Image Home 2009


  1. You map a folder to a disk drive letter using the Windows subst command. For example:

    subst X: C:\

    See also Microsoft TechNet Article: Subst.

  2. You then attempt to perform a scheduled backup of the volume mapped via the subst command;
  3. When doing so, you get an error similar to the following ones:

    Failed to open file. Cannot find path

    Failed to backup file or folder

    Error occurred while opening the file

  4. Running the backup task manually (as opposed to running it on schedule) works fine.


When Acronis products back up via schedule, the backup task is ran as a service. The Acronis service does not have access to volumes mapped with subst. If the backup runs direcly without schedule, the backup is started by the user, which has access to the mapped volume. Hence manual backups work, but the scheduled backups do not.


Currently, volumes mapped with subst are not supported. Instead select the files you would like to back up directly.

More information

Feel free to contact Acronis Customer Central if you have further questions.


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