Acronis Backup Cloud Known Solutions

Your Acronis Backup Cloud quick troubleshooting kit. Below are the most recently published and the most popular articles. The solution you are looking for is most probably right here.

Most recent articles

Slow detection of some USB drives

Create special registry keys to fix this issue


  1. After you install Acronis Backup 12.5 on the machine, certain USB drives/keys are not instantly detected. It takes 2-5 minutes for the drive to acquire a letter and be accessible in Windows Explorer.
  2. If you stop Acronis Managed Machine service, the same USB drives are detected instantly.


Hardware incompatibility: some specific devices incorrectly process standard commands issued by Acronis product components.

Backup of a large number of SQL databases fails with "VSS writer 'SqlServerWriter' has failed to process the snapshot"

You have an SQL server with a vast number of SQL databases (500+) in one SQL instance.

Backup of this server fails with:

Error code: 50281
Module: 16
LineInfo: 0x3FEC04E376B89DAF
Fields: {"$module":"ArsDbBackupProvider_vsa64_10170"}
Message: VSS writer 'SqlServerWriter' with class ID 'A65FAA63-5EA8-4EBC-9DBD-A0C4DB26912A' has failed to process the snapshot. To troubleshoot VSS issues, download and run Acronis VSS Doctor available at

Exclusion of a partition does not work

You use Acronis Backup Cloud version 7.7 or Acronis Backup 12.5 with cloud management.

You create an Entire machine backup plan and select 'Version 12' backup format. In the exclusions, you specify one of the partitions, for example E:, to be excluded from the backup.

The specified partition is not excluded from the backup.

Local storage usage calculated twice

You are backing up to a network share.

When you check local storage usage, you notice that it shows double the amount of occupied local space.

Agent registration fails with "Agent is already registered. Please, deregister agent in Backup Console"

You are installing Acronis agent of version 7.7 (build 10170).

Installation fails at agent registration step with this error:

Agent is already registered. Please, deregister agent in Backup Console.

If you try to register the agent manually, registration fails with this error:

Agent is already registered.
Please, deregister agent in Backup Console.


Unregistration of agent in AMS failed.

"Failed to find directory '/lib/modules/2.6.32-504.16.2.el6.x86_64/build' that contains the kernel source code" error

You have Acronis agent installed on a Linux machine. You have updated the agent to version 7.7 (build 10170). After update, backup of the Linux machine starts failing with:

None of the items selected for backup were found.

In update logs, you can find these messages:

Failed to find directory '/lib/modules/2.6.32-504.16.2.el6.x86_64/build' that contains the kernel source code.
The kernel source code or kernel headers require installing.

Error when backing up OneDrive folder

After you update Windows to version 10.0.17134, a backup that includes OneDrive folder fails with an error similar to the following:

(error might be different if version 11 archive format is used)

Error code: 12
Module: 4
LineInfo: 0xC8D8731CE106F9CA
Fields: {"$module":"archive3_adapter_vsa64_9940"}
Message: The file is read-only.

Physical Data Shipping option is missing for Entire Machine backup
  1. You log in to the Backup Console of Acronis Data Cloud 7.7.
  2. You create a backup plan for the Agent that is still is of the old build 4670.
  3. With the default Entire machine plan, the Backup Option of Physical Data Shipping is missing. The option might be present for Disks or Files/Folders backup plan, but disappears while the plan is created.
Size of individual slices (recovery points) is missing

In Acronis Backup Cloud 7.0 and earlier, it was possible to check the size of backup slices.

Backup fails with "Failed to parse the XML"

The backup of any kind fails with the following error message:

Failed to parse the XML.

| error 0x3b0001: Failed to parse the XML.
| line: 0x9a79f20828bcab0
| file: e:\72\enterprise\mms\managers\location\impl\manager.cpp:832
| function: LocationManagement::LocationManagerImpl::AddLocation
| IsReturnCode: 0x1
| $module: disk_bundle_vsa64_4670


Most viewed articles

"Failed to Connect to the Process" error

You may get the error when starting a backup plan destination to SAN, complex RAID or dynamic disk arrangements, or Cloud storage. To fix it, add a value StartTimeout in Windows registry.

"The shadow copy provider had an unexpected error while trying to process the specified operation"

VSS-Backup fails with "The shadow copy provider had an unexpected error while trying to process the specified operation". To solve this issue, troubleshoot the VSS provider mentioned in the message.

"Failed to read the snapshot"

You attempt to perform a disk or partition backup that fails with the following error: "Failed to read the snapshot."

"Backup failed" alert

A backup did not complete successfully.

"Backup finished with warning", "Activity finished with warning", "Activity failed" alerts

An operation in Acronis Backup 12.5/12, Acronis Backup Cloud, or a customized backup solution based on Acronis Backup Cloud finished with a warning message or failed.

"Backup did not start" alert

This alert is displayed when our product detects that a backup activity was not started at the scheduled time. For example, if a machine was turned off during scheduled backup time, this alert will be displayed the next time it is connected to the Management Server.

"Link target was not backed up" or "The file is out of backup scope" warnings

You create a backup. Backup completes with warning "Link target was not backed up" or "File {1} pointed by symlink {0} will not be backed up because the file is out of backup scope." Warning notifies that symbolic link target is not included in the backup.

Machine is offline in Backup Management Console

After successful installation, the machine is offline in the Backup management console.

"Backup status is unknown" alert

This alert appears when the agent machine is offline during a scheduled backup. In this case, our Management Server has not received information whether the backup is running successfully or failed.

"VSS writer 'SqlServerWriter' with class ID 'A65FAA63-5EA8-4EBC-9DBD-A0C4DB26912A' has failed to process the snapshot"


Backup fails with the following message:

You are reporting a typo in the following text:
Simply click the "Send typo report" button to complete the report. You can also include a comment.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
2 + 3 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.