BA4801 Could not mount Data container

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BA4801 Could not mount Data container

by bniknar » Fri Apr 07, 2017 4:30 am


I've been getting that error for the last two system protection backups (into a 3TB VHDX file on a NAS). The system (Windows Server 2012R2) recently had a emergency reboot during a backup and I suspect that the container wasn't unmounted correctly.

How I tried to resolve:

    1. Browse to the container using Windows Explorer and mount manually. This failed, with an error about invalid partition or volume
    2. Went into Disk Management, attached the VHDX and assigned drive letter Z. Worked great, the system saw the partition as healthy, could browse Z: and see all past backups. Them I took the VHDX offline and detached.
    3. Back again to Windows explorer and mount manually, failed with the same error.
    4. Run system protection backup manually, fails again with Can't Mount Data Container

I repeated #2 thru #4 about 6 times, each time #3 would give me the same error and #4 the manual backup would also fail. Yet the VHDX is still valid as I can browse it successfully when I attach it via Disk Management.

Any ideas?
Posts: 12
Joined: Mon Feb 13, 2017 12:57 pm

Re: BA4801 Could not mount Data container

by casey.burns » Fri Apr 07, 2017 6:20 am

Hi there,

My name is Casey, and I'm with the BackupAssist team. Thanks for posting on our forum.

Whenever you are attempting to manually mount a data container, we recommend that you use the disk management console. There are known problems with Server 2012 machines being able to mount VHD/VHDX files via Windows explorer. For more information on our recommendations regarding manually mounting containers, check out the link below. ... container/

Once you've verified that the container is mountable and has the data inside, you'll need to detach the VHD (Remember to remove the drive letter from the mounted file first). This will ensure that the container is put in the position where it can be properly mounted when the backup starts.

I hope this helps, please let me know if you have anything further to add.
Kind regards,

Casey Burns
BackupAssist Support
Posts: 148
Joined: Mon Sep 10, 2012 10:10 am

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