Fixed: Windows Backup Failed to Dismount the Backup Image

This article will show you how to fix the error: Windows backup failed to dismount the backup image. And a better way to back up system to external hard drive.


by Delia Updated on December 30, 2022

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Windows backup failed to dismount the backup image


I am running Server 2008 R2, but when I attempt to back up the Server to an external USB drive via Windows Server Backup, I get the message: Windows Backup failed to dismount the backup image. Any ideas will be appreciated.

Usually, this problem “Windows Server backup failed to dismount the backup image” occurs when using the Windows Server Backup tool. If you have met this error when you try to back up system to an external hard drive, you can check the hardware at first, because this error was probably caused by hardware issues.

If there is nothing wrong with the hardware, you can try to back up a small file instead of system to see if Windows Server Backup function works or not. If it works well, you can try to back up system to another volume (local disk is preferred) instead of the external hard drive. 

Windows Server

Reliable Windows Server backup software - AOMEI Backupper

In fact, Backing up with Windows Server Backup is easy to fail for different errors, and sometimes, you are not able to fix Windows Server Backup. Therefore, if you want to do backup, you’d better choose a professional backup software like AOMEI Backupper Server, which can back up Windows Server to external hard drive with only a few steps.

With clear interface and user-friendly design, you can use it easily. It also provides a Schedule Backup feature that allows automatic Daily/Weekly/Monthly backup. What’s more, with incremental or differential backup, you can keep your system backups updated while saving disk space. With a backup in hand, you can restore system at any time.

A better way to back up server system to external hard drive

Follow the detailed steps to learn how to back up system to external bard drive:

Step 1. Download AOMEI Backupper Server, install and launch it.

Download Free TrialWin 11/10/8.1/8/7/XP
Secure Download

Step 2. Click System Backup under Backup tab. You can also choose Disk Backup, Partition Backup or File Backup as you like.

System Backup

Step 3. You can edit the default Task Name to distinguish it from other backups. System and boot related partitions are listed automatically. Select a destination path to save system image file.

Select Backup Destination

Note: You can save a system image to a local disk, an external hard drive, and you also can save to NAS devices or network share by clicking Share/NAS.


Step 4. Click Schedule Backup at the bottom of backup interface to set up a backup schedule. You can choose Daily/Weekly/Monthly/Event triggers/USB plug in backup or Full/Incremment/Differencial Backup.

General Settings

Step 5. Click Start Backup to backup system to external hard drive.

Start Backup


“Windows backup failed to dismount the backup image” is just one of the errors when using Windows Server Backup tool. There are still some other errors like “Windows Server Backup incorrect function”, “Windows Server Backup Service Missing”. So, using AOMEI Backupper to back up system is a better choice. With this software, you can restore the system directly when system crash, and you also can transfer system by cloning without reinstalling.

Delia · Editor
Delia owns extensive experience in writing technology-related blog posts, and has been a part of AOMEI since 2020 to provide expertise in data security and disaster recovery. She works with Windows operating systems, SQL databases, and virtualization platforms such as VMware and Hyper-V, specializing in troubleshooting and advising on data protection and migration.