@Diana Piloya It looks like the scratch folder space doesn't have enough space or may be the volume you are trying to backup has huge number of files which is causing the failure. For now, please check if scratch folder is valid and accessible - https://learn.microsoft.com/en-us/azure/backup/backup-azure-file-folder-backup-faq#how-to-check-if-scratch-folder-is-valid-and-accessible-
Also, ensure that cache folder has enough space. The cache folder volumes should have free space that equals at least 5-10% of the total size of backup data.
EDIT: Can you check the CBEngine logs from C:\program files\Microsoft Azure Recovery Services Agent\Temp and see if that guides you to troubleshoot the issue further?
Hope this helps!
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