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Problem with Windows VM in AWS not Booting after Recovery to vCenter

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An administrator may experience a Windows VM post-recovery to vCenter from AWS is not booting.

Root Cause

  • AWS may update the drivers and other components stored in the Amazon Machine Image (AMI) offered to customers when building a native VM (born in AWS).

  • ZertoTools for Windows was run using the "Install the latest AWS PV Driver" option on a VM running in vSphere prior to migration to AWS and the 'Zerto Import for all volumes' import method was used during migration.

  • The 'Zerto Import for data volumes' or 'AWS Import' import method was used during migration to AWS (these methods do not require ZertoTools for Windows).


When attempting to use test failover, live failover, or move from AWS to vSphere (vCenter), an administrator may experience the following symptoms:

  • The VM will power on and load the BIOS.

  • The VM will not load the guest OS, and no error message is displayed when viewing the guest VM console.

  • Restarting or powering the VM off and on will not change these symptoms.

  • The AMI used to create the VM has been updated by AWS, including updated virtual drivers.


In these cases, Zerto has found a workaround using the following steps:

  1. Log on to MyZerto and navigate to Support & Downloads - Software Downloads - Tools.

  2. Download the 'AWS PV driver downgrade script' and run the script on the instance protected in AWS prior to attempting a failover or move.

  3. The script will downgrade the AWS PV drivers from the latest version to version 7.4.6.

  4. Before initiating a failover or move, select a checkpoint created after the script was run successfully.

This script supports the following operating systems:

  • Microsoft Windows Server 2016

  • Microsoft Windows Server 2012 R2

  • Microsoft Windows Server 2012

  • Microsoft Windows Server 2008 R2

Note: For other operating systems, please review the Interoperability Matrix for Zerto Virtual Replication .

Note: When running the downgrade script, any Remote Desktop connection to the AWS instance will be interrupted for up to 10 minutes. The connection will be restored once the driver downgrade is complete.