To back up machines in an ESXi Free environment, regular Acronis Agent for Windows/Agent for Linux (as opposed to Acronis Agent for ESX/ESXi or Acronis Agent for VMware) should be installed inside the virtual machines. Agentless backup is not supported.

Versions 1.5, 5.0, 5.1, 5.5, 5.6, 8.0, 8.1 are supported

Unlock the partition using diskpart

You attempt to run a backup from virtual guest and get this error. Change location of virtual guest or change block size of used datastore, so that the datastore blocksize and blocksize of virtual guest matches.

The Virtual Machine is detected as replica if there is SourceArchive property in Virtual Machine's annotations. Delete the "SourceArchive" part to fix the issue


  1. You want to update several Hyper-V agents at once under Settings - Agents,
  2. When you select required agent machines, the following error is displayed:

More than one Agent for Hyper-V is selected. Simultaneous update of multiple Agents for Hyper-V is not possible. Please update these agents one by one.

If you have virtual machines using duplicated BIOS UUID, you cannot see all existing virtual machines. Only one of them will be displayed. To fix this issue, you should change the BIOS UUID in one of the affected machines manually

This article applies to:

  • Acronis Cyber Backup & Recovery 11.5
  • Acronis Cyber Backup 11.7 - upgraded from earlier versions
  • Acronis Cyber Backup 12/12.5 - upgraded from earlier versions


Backup or another activity with a VMware ESXi VM fails with the following error:

SOAP 1.1 fault "":ServerFaultCode[no subcode]
"Failed to authenticate with the guest operating system using the supplied credentials"


  1. You have set up some Agents for VMware (Windows or Virtual Appliance) connected to a vCenter/ESX(i) host.
  2. Some virtual machines do not appear in Cyber Protection console after recovery or physical to virtual conversion


Current Acronis Cyber Protect products use VMware "InstanceUUID" property in order to identify each virtual machine. If one or more machines use the same InstanceUUID then only one machine will appear in the console.


You are using Agent for VMware or Agent for Hyper-V or Agent for Scale Computing HC3 (in Acronis Cyber Protect 15) to protect virtual machines in agentless mode.

In addition to agentless backup, you installed one or several of the following Agents inside a VM:

  • Agent for Windows
  • Agent for Linux
  • Agent for SQL 
  • Agent for Exchange

Machine with Agent appears twice in the list of All devices: once as a virtual machine, once as a virtual machine with an agent inside.

Acronis Cyber Protect Home Office and Acronis True Image has been tested and is guaranteed to work with just one virtual machine format: Parallels Desktop 14. It is supported by Mac version of Acronis True Image 2019 and later.

Backup and recovery of Parallels Desktop 14 virtual machines

One of the unique features of Acronis Cyber Protect Home Office and Acronis True Image 2019/2020/2021 for Mac is its unrivaled support of Parallels Desktop 14 virtual machines backup, as part of disk backup on a Mac host:

You are backing up virtual machines by an Agent for VMware or Hyper-V (agentless backup). Backup notifications are enabled. Notifications contain only the name of the host machine or the name of Agent for VMware (Virtual Appliance or Windows Agent) machine name in the e-mail subject and body.


You have Acronis Cyber Infrastructure rolled out in VMware environment.

You want to create VMware native snapshots of virtual machines serving as Acronis Cyber Infrastructure (ACI) cluster nodes and be able to restore from these snapshots.


When setting up snapshots, take the following into consideration:


  • You create backup of a machine which has Acronis Agent for Windows or Linux installed
  • You run this backup as VM (“Instant Restore” feature) and finalize it via Agent for VMware/ Hyper-V


  1. You are trying to back up or recover virtual machines on ESX/ESXi server using Acronis Agent for ESX/ESXi or Agent for VMware
  2. Operation fails with an error message similar to the following one:

    Cannot back up virtual machines of the ESX/ESXi server because the "vStorage APIs" feature is not installed on the server


VMware vStorage APIs are not installed on the ESX/ESXi server.

Step-by-step description of what happens when you choose to back up a virtual machine using the Agent for VMware (Virtual Appliance) or Agent for VMware (Windows)


  • After performing V2V restore (VMWare backed-up machine to Scale HC3), you are facing the following issues:

1. The VM runs normally, but cumulative updates failing with the error "0x8007054f"

2. Not possible to replace the VirtIO Red Hat SCSI controller driver with a new version.


Issue in the product.

This issue will be resolved in one of the upcoming updates.

In the meantime, please follow the workaround below


VMware VM replication reaches 100% and hangs. No error or warning is displayed.

Logs from /var/run/log/hostd.log on ESX host contain a message similar to the following :

2021-08-13T22:28:12.116Z error hostd[2100679] [user@6876 sub=Req@vim25/] length of HTTP request body exceeds configured maximum 100000


Limitation on the VMware side: it does not allow SOAP API requests longer than 100000 symbols


To work around the issue, increase the maximum length of API requests in config: