"There was a failure in preparing the backup image of one of the volumes in the backup set."

Hi,

Thanks for your post.

Could you please check the event viewer for more information？ That may indicate the main cause.

And in addition, you could check the thread discussed before, that might be helpful.

https://social.technet.microsoft.com/Forums/office/en-US/20ab10a8-fb39-451f-9076-46a6188b2139/server-2012-backup-fails-while-preparing-one-of-the-local-volumes-with-the-mounted-backup-volume-is?forum=windowsbackup

Best Regards,

Mary

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