There are two possible causes. Please read the article to fix the issue
List of possible causes and solutions
Troubleshooting issues with Wake-on-LAN in Acronis Backup Advanced
How to remove orphaned activities using a special script
Description of the Wake-on-LAN technology implemented in Acronis Backup Advanced
After restart of machine with Acronis Management Server, several machines are grayed out. As a result the centralized backup plans are not running.
This error message can be safely ignored
To fix the issue, edit Windows Registry or download and replace a DLL file
The delays may happen if the License Server is on a remote machine
Change Acronis databases to Simple Recovery model
A single-pass backup (aka application-aware backup) is a disk backup containing metadata of VSS-aware applications that are present on the disk. This metadata enables browsing and recovery of the backed-up application data without recovering the entire disk or volume.
Single-pass is available for machines running SQL Server, SharePoint Server and Active Directory. Single-pass is not available for Microsoft Exchange.
Having Acronis Backup, you will see following new part (on local management or centralized management console) when Create backup plan:
If the Hyper-V service is stopped, you will see the "Failed to Obtain an Instance of Service Class 'Msvm_Virtualsystemmanagementservice'" entries in Acronis logs. To fix this issue, you have to start the Hyper-V service manually on Hyper-V host
The most probable cause is that the specified address is incorrect or the machine is unavailable
An attempt to connect to an Acronis Agent or Acronis Management Console fails with an error similar to the following one:
Failed to establish connection using the specified credentials
The user under which you are trying to connect does not have enough privileges.
To back up the system encrypted with BitLocker you will need to create an image from Windows
You observe one of these symptoms:
1. The occupied space on the Account tab of Acronis True Image shows the amount of data stored in Acronis cloud, but when you open Family dashboard and want to download files from Acronis cloud, the Web Recovery page does not show any backups.
2. You are trying to recover the data from the Web Recovery page but when you click on your backup or click 'download' on the file, you get an error message stating "The server is not available at the moment. Please try again later".
Table of trial limitations of Acronis products
Backup to a NAS device through FTP may fail
How to upload files to Acronis FTP Server