45891: Acronis Backup for VMware 9: "Guest OS is not supported" Error during Application-Aware Backup Task Creation

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Last update: 06-04-2016

When "Guest OS is not supported" error appears while creating an application-aware backup task, make sure that the .vmx of the backed up VM contains proper guestOS value which corresponds the real guest OS installed.


  1. You run through a backup wizard and select an Exchange/SQL/SharePoint VM to be backed up;
  2. On the fourth step you check the option to perform application-aware backup;
  3. After providing credentials you see the "Guest OS is not supported" message:


The problem is that the .vmx file contains wrong guestOS value which does not correspond the real guest OS installed inside the backed up VM.


  1. Power off the problematic VM
  2. In the vSphere client right-click on VM and go to Edit settings
  3. Go to Options -> General Options
  4. Select Guest Operating System: for example Windows, Microsoft Windows Server 2012 (64-bit). This setting must be set in accordance with the real OS installed inside the VM. If this setting is already set properly then proceed to the next step.
  5. Power on the VM.

If the problem still persists then pick up the .vmx file of the problematic VM and contact Acronis Support for assistance.

More information

The changes to Guest OS property are applied to .vmx only upon VM start up, so it is required to power off and on the VM in order to apply changes. The check for the supported guest OSes is done within vmProtect 9 by analysis of the .vmx file, so it's crucial that this file contains valid information.