An administrator may encounter failures when attempting to add VSS-enabled checkpoints for VMs with the Zerto VSS Agent.  This failure results in no checkpoints being generated by the ZVM, and the Event Viewer on the affected VM displaying VSS errors containing "Access Denied" messages.   This article explains the cause and the solution.    


The failure to add VSS-enabled checkpoints occurs due to a problem with the permissions granted to the the user configured to run the Zerto VSS Agent.  In order to resolve this issue and allow the Zerto VSS Agent to take the VSS checkpoints, follow these steps to modify the COM Security permissions for the user running the VSS Agent on the VM:


  1. On the relevant VM, open dcomcnfg.exe.

  2. Browse to Component Services > Computers, and right-click on the relevant computer.

  3. Click on the COM Security tab.

  4. Click Edit Default under Access Permissions

  5. Add the 'Network Service' user, or whichever user is configured to run the scheduled task, to the users list, and grant it Local Access permissions.

  6. Click OK and close the My Computer window.