By Ivy / Last update September 26, 2021

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The case

"I am trying to get a Windows Server 2012 box to backup to a NAS. However, Windows Server backup failed every time no matter what I select to backup (System State, BMR, single file, etc), the job will fail giving an Incorrect Function error. Can anybody give some insight into what could be causing the Incorrect Function error?"

Windows Server Backup Incorrect Function

Reasons and solutions for Windows Server Backup incorrect function

Sometimes, you may meet this error in different situations, for example, backup files or folders to network share or external hard drive with Windows Server Backup, Restore system image with bootable media, etc. And you may receive different error message in the following:

  • The backup process started but then failed with Windows Server Backup “Incorrect Function”;
  • There was a failure in preparing the backups image of one of the volume;
  • The system image restore failed. Incorrect function (0x80070001);
  • There was a failure in preparing the backup image of one of the volumes in the backup set. Incorrect function.

What’s wrong with it and how to fix this? Let’s see the reason and solutions for this issue.

Reasons to Windows Server Backup incorrect function 

1. The issue occurs because the folders or libraries that you are trying to back up or restore include a reparse point. If the reparse point points to a volume that uses the FAT file system, it will cause this issue.

A file or directory can contain a reparse point, which is a collection of user-defined data. A reparse point may be used to point to a file that is temporarily relocated on a different drive. For example, a reparse point would allow a folder such as C:\DVD to point to Drive E, the actual DVD drive.

2. Windows Backup sometimes fails to read the last sector on the volume. You may receive windows server backup error incorrect function if the last sector is corrupted.

3. The backup path is over 110 characters when you restore system image. 


Solutions to Windows Server Backup failed to complete incorrect function

In the following, you will learn 4 fixes to Windows Server Backup error incorrect function, namely, remove the reparrse point from library, shrink volume with disk management, use shorter backup path, or different backup path to tore backup images. For details, please check them below.

Fix 1: Remove the reparse point from library

To deal with Windows Server Backup completed with warnings incorrect function caused by reparse point, you should remove the reparse point from the library, and then create a backup again. 

First, you should know where the reparse point folder is. To locate reparse point folder or its subfolder, do as the following.

1. Click Start button, type CMD in the Search program and files box and then press Enter.

2. In the Command Prompt window, type DIR /AL /S and then press Enter. The list of JUNCTION (one type of reparse point) list is displayed.

Command Prompt

Note: You see several entries that say "junction" and the location to that the entries point. Junction point is another name for reparse point. When a program tries to write to a directory that is really a reparse point, those files are sent completely blindly to the other directory instead.

After you find reparse point, delete it. To delete mounted volume reparse point, follow these steps. 

1. Locate the reparse point you found, right-click it and select Properties.

2. In the General tab, confirm the folder Type is Mounted Volume and then delete this folder.

Mounted Volume

Note: Before deletion, you need toback up content for this reparse point (in this case, the FAT volume or the mounted volume), select the absolute path of this location in the Windows Backup configuration user interface.

Fix 2: Shrink volume with Disk Mangement 

To deal with Windows Server Backup failed to complete incorrect function caused by the last sector is corrupt, you can try to shrink or extend the volume, where the backup is failing, by 5-10 MBs.Here will take shrink volume as an example: 

1. Press Win+R and type “diskmgmt.msc” to open disk management. Right-click the volume you need to shrink and select Shrink volume.

Shrink Volume

2. Enter the amount of space to shrink in MB and click Shrink.

Tip: As mentioned earlier, Extend Volume can also be helpful when you encounter the Incorrection function error due to last sector. Open Disk Management, right-click it and select Extend Volume, then set the MBs you want to extend and finish the rest of steps with on-screen instruction.

Fix 3: Use shorter backup path 

As mentioned earlier, if the backup path is over 110 characters, you may encounter the Icorrect function error when restore. Thus, it's suggested to use shorter backup path when backup to network share or directly create a WindowsImageBackup on the network share and copy the folder with your computer name into it.

Note: Usually, Windows Server Backup will stores backups at the following path: backupstoragelocation > WindowsImageBackup> ComputerName. If you store the backup image at the network location, it could be \\\networkshare folder\WindowsImageBackup\computername.

Fix 4: Use different backup path to store backup images 

If you use a NAS as a backup path, but failed with Incorrect Function error, you can try to backup files to external hard drive or use iSCSI LUN to store backup images. It's said, both methods work sometimes. You can try to configure iSCSI and use LUN as backup pth first.

Here take WD Cloud EX4 as an example, below are the steps. In WD Cloud EX4, it has storage option that include the iSCSI option, which allows you to use it as a local disk, but is accessed over a network. If you are using other NAS, you need to find how to create a LUN on it.

1. Open the network path of your WD Cloud EX4 in a browser, and select Storage > iSCSI in order.

WD Cloud Ex4 ISCSI

2. Then, scroll down to the Create iSCSI Target option and click it. And you will be asked set a name and the size, just do it and complete the rest of steps.

3. Go back to your server and search iscsi initiator and select it. It comes along since Windows Server 2008. If you are using previous server, Windows Server 2003, for example, you need to download and install it first.

4. In the iSCSI Initiator Properties window, type the IP of your NAS and click Quick Connect....option. Then, you will see the name of the LUN's available on your server, just select the one you want to connect.

ISCSI Initiator

Note: Depending on the NAS you are using and security settings on the LUN, you may need to use the other tabs in following to get it connected.

5. After connect LUN, you still need to format disk and assign a drive letter for it using Disk Management. Type diskmgmt.msc in the Run box and hit OK to open it. Then, right-click the disk and select Format...option, and do the rest of the steps. 


After finishing above, you can continue to create a backup with Windows Server Backup, or directly use Wbadmin command to make it. 

An easy way to solve Windows Server backup incorrect function

If the solution mentioned above does not solve the problem, or you think the solutions are complicated, you can try an easier solution – use third-party software. As a matter of fact, Windows Server Backup still leaves something to be satisfied.

When you try to backup using Windows Server Backup, you cannot use any volumes not formatted with NTFS as backup source or backup target. Besides, Windows Server Backup in 2008/2008 R2 cannot support volume greater than 2TB. And many errors you have not encountered: The parameter is incorrect (0x80070057), The mounted backup volume is inaccessible, Windows Server Backup one of the specified source volumes has an invalid format, etc.

If you want to find an easy way to solve those issues, you can turn to AOMEI Backupper.

Powerful Windows Server backup software - AOMEI Backupper Server

AOMEI Backupper Server is a professional Windows Server backup and recovery software. With it, you can backup files and folder, partitions, hard disk or only system very easily. Compared to Windows Server Backup, it offers more powerful functions.

  • It supports 5 backup solutions, namely System Backup, Disk Backup, File Backup, Partition Backup.

  • You can set scheduled backup to backup at a pre-set time automatically: daily/weekly/monthly/event triggers/USB plug in.

  • Besides full backup, it also supports incremental and differential backup types that can help save storage space.

  • It allows you to backup file size large than 2 TB. Also, it supports both NTFS and FAT32 File System.

  • It's capable of backing up files or folders, system, disk or partition to different location effortlessly, such as, network drive, external hard drive, NAS, etc.

If anything bad happens to your system or data, AOMEI Backupper allows you to restore your computer to its previous state with just a few clicks. You can even restore system to dissimilar hardware with the help of its "Universal Restore" feature.

How to backup Windows Server with AOMEI Backupper

Step 1. Download AOMEI Backupper, and launch this software. It will bring you to the main interface.

Download Free Trial Win 10/8.1/8/7 & Server
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Step 2. Click Backup at the left panel, and choose System Backup.

System Backup

Step 3. You do not have to choose source partitions, AOMEI Backupper has chosen them automatically. Just click the column below to select another location as the destination path to store your system image files. The destination location can be verified like internal hard drive, external hard drive and NAS.

Start Backup

▶ Options: you can encrypt your backup and enable email notification, etc.
▶ Schedule: you can create automatic backup tasks. There are six schedule modes available: “Daily”, “Weekly”, “Monthly”, “Event triggers”, and “USB plug in”.
Scheme: you can enable Disk Space Management that can help automatically delete the previous backup images.

Step 4. Finally, click Start Backup to confirm.


That’s all for how to fix Windows Server 2012/2008/2016 backup incorrect function error. If the 4 methods cannot help you solve the problem, you can try the Windows Server Backup alternative - AOMEI Backupper Server. With the help of AOMEI Backupper, you can backup and restore in a few clicks and do not have to worry Windows Server Backup incorrect function issue anymore. 

And if you want to protect unlimited PCs and servers within your company, you may choose AOMEI Backupper Technician Plus. It offers unlimited billable technical services to clients. It also enables you to copy installation directory for portable version creation.