Application-aware backup fails with one of these errors:

Error 1

Error code: 34865165
Fields: {"$module":"aavb_backup_command_addon_vsa64_23140"}
Message: Failed to get the metadata from the 'VMware Snapshot Provider' extension library.
Error code: 65520
Fields: {"$module":"aavb_backup_command_addon_vsa64_23140","code":2147942402}
Message: The system cannot find the file specified

When contacting Acronis Support with a technical issue, it is recommended to have Acronis System Information at hand


Backup of a Windows machine fails with error:
Logon failure: unknown user name or bad password.


Acronis Cyber Backup agent receives this error from Windows while trying to access backup source or target.


Operation (backup, recovery, cleanup) fails with the following error:

Windows error: (0x8007051F) There are currently no logon servers available to service the logon request


Backup to NAS or a different activity(replication, validation) fails with:

 Windows error: (0x80070544) The validation information class requested was invalid


  1. You save backups to an unmanaged location using Version 12 archive format 
  2. Two or more backup archives have the same "Date modified" value

  1. You have a Windows VM with dynamic disks.
  2. You create an agentless backup of this VM using Virtual Appliance.
  3. When you check the backup archive contents, you notice that drive letters are displayed incorrectly.


  1. You are backing up a SharePoint Server.
  2. Backup fails with:

Error code: 54
Module: 482
LineInfo: 5c71ebf434f0c47a
Fields: $module : disk_bundle_vs_38774
Message: Failed to collect all of the data required for single-pass backup of Microsoft SQL Server.
Error code: 4354
Module: 87
LineInfo: e4fe5c9fd5e63de8
Fields: $module : aaib_mssql_backuper_vs_38774


You created Acronis Rescue media on a Mac.

When you attempt to back up the machine with macOS using rescue media, the Backup option is not available. Only recovery can be performed.


The current product design does not support backing up macOS using bootable media. 

This applies to all types of bootable media: ISO downloaded from the website, bootable media created under macOS, bootable media created under Windows or Linux.

You set up a backup plan of Windows machine(s) with Policy Rules: [Disk 0] in Items for backup.

Backup fails with errors similar to:

Cannot resolve inclusion rule '[Disk 0]'.

Disk 0 has not been found while processing the 'Disk by number' template

  1. You create a backup using Version 12 format.
  2. An operation with archive (e.g. applying retention rules) fails with the error message

    Failed to lock the file


You are backing up data to QNAP NAS.

When the activity is almost complete, it fails with:

The credentials for location are not specified


Outdated NAS firmware.


Update NAS firmware to the latest version.

If the issue reproduces with the latest version of firmware, collect system information from the affected agent machine, details about NAS(model, firmware version) and contact Acronis Support.


You have installed Acronis Backup Cloud agent for SQL and created a backup plan for a SQL instance.

Backup task fails with this error: "There are no SQL writers." or "The backup of this SQL Server has failed because of a VSS snapshot failure: No SQL writers are found in the operating system."


Backup to Acronis Cloud fails with the following error:

Mismatching backup types. Please reconfigure the cloud backup and try again.


Information about backup type in the script does not match the type of the created backup. Details are under investigation.


Resolving this issue requires manually modifying the backup scripts. Please contact Acronis Support for assistance, with a reference to this article.


After agent update to Build 24600 or 24476, Acronis Scheduler randomly generates errors in Windows Event log:

Scheduler failed to run task with GUID '15C608E6-C6BD-4C21-B41C-E10368FDACD8' because of error 2 (Failed to find the file (folder) or the key (value) in the registry.)

GUID is different on each device.


Issue in the product. Obsolete service tasks are not deleted automatically during update.


This issue is fixed in Build 26172, please update to the latest build.


File-level backup fails with:

Fatal protocol error


You created a backup in Version 11 backup format (file extension .tib) using Agent version 26986 or earlier.

Then you updated the Agent to build 27147 or newer and run the backup to the same archive.

Backup fails with:

Archive with the same name already exists


  1. You download a Bootable media and get a registration token for it
  2. You boot a machine with the Bootable media and register the media on Management Server with the registration token
  3. Go to Recovery and select Cloud vault. No backups are shown and the following message appears:

    The selected location does not contain backed up data


Issue in the product.


This issue has been fixed in Acronis Cyber Protect 21.10.

This article applies to:

  • Acronis Cyber Protect Cloud
  • Acronis Cyber Protect 15 - Cloud deployment


  1. You are backing a Windows machine with LVM disks,
  2. Backup finishes with a warning "Failed to detect OS"


Issue in the product.


  1. You have set up a Disks backup. The initial backup (and the following incremental backups, if any) worked correctly
  2. You install an upgrade to macOS.
  3. When you try to run an incremental backup after macOS upgrade, the operation fails with:

    The last backup has failed. No current partition


macOS upgrade changed the unique volume identifier for the source disk, while the backup task configuration still refers to the old volume identifier.


1) Basic error message stack in Backup Console:


Common I/O error.

2) Details of error message in Backup Console (click on the Details button):


DFS Replication is used on the server.

You set up a CDP backup task to protect replicated folders.

The initial full backup is created successfully, but after that CDP backup does not run. No error is displayed.


CDP is not compatible with DFS Replication.


Disk/partition backup fails with: 

Windows error: (0x80070001) Incorrect function


Backup, replication or another activity fails with:

The path <path> does not exist.

For example: The path "F:/" does not exist.

Or, in older builds:

Windows error: (0x80070002) The system cannot find the file specified


  1. You enabled two-factor authentication in Cloud console 
  2. Acronis Cyber Backup/Protect software is installed as on-premises deployment
  3. You configure backup to Cloud Storage. Backup fails with the following error:
    The credentials for location <account> are not specified.
    Failed to authorize the user.



You are backing up a VM with Active Directory; application-aware backup is enabled. A new dedicated domain administrator account was created on the VM specifically for application backup with Acronis Cyber Protect (see Required user rights).

Backup plan completes with a warning message:

The credentials are incorrect.


1) An Entire machine backup fails with the following error:

ASYNC: Full barrier action job


1) 以下のエラーが表示され、全体コンピュータのバックアップに失敗します:

「ASYNC: Full barrier action job」


  • You need to migrate a large number of cPanel hosts running on CloudLinux 6.10 or 7.9 to CloudLinux 8.x (e.g. CL8.5)
  • You would like to be able to continue using the same TIBX files and to keep using group plans/multi-machine plans applied to these hosts


Please follow the steps below to migrate:

1. Perquisites:

You start a backup plan for the first time. After the first backup has not completed (for any reason), you want to delete this incomplete archive, but cannot find it under Backups. Or you notice, that space used in Acronis Cloud is larger than your backups occupy.