Error in backup 0x807800C5

Thanks! This worked for me when I didn't perform a backup with the system image.

Es ist so typisch von Microschrott, dass sie es selbst nach Jahren NICHT schaffen, eine funktionierende Imagesicherung ihres eigenen Systems hinzubekommen :(

Der Abbruch bei 57% erfolgt nur, wenn auch ein Systemabbild erstellt wird, die Sicherung der Dateien und des Windows-Verzeichnisses funktioniert dagegen (meist) zuverlässig.

Ich empfehle zur Imagesicherung der Systempartition Software von Drittanbietern, konkret "Drive Snapshot", das genial einfach und absolut zuverlässig funktioniert!!!

www.drivesnapshot.com

Problem Solved in my case ! 

I enable on Synology SMB3 . 

I disabled smbv1 on Windows 10 client , reboot pc and voila ! It works !

See https://support.microsoft.com/en-us/kb/2696547  to enable or disable smb version

I also received this error.

finally found the following solution:

http://superuser.com/questions/508932/windows-backup-failed-with-error-0x807800c5

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FYI, instead of adding EVERYONE permissions, try adding SYSTEM permissions. I was getting error 80070005 when I was trying to backup to a network share on a local drive (the only way to backup to a subfolder). Although giving full access to EVERYONE on both the folder and the share was sufficient to stop the error, such access was unacceptable. I started to narrow down the accounts, and it turns out that giving the SYSTEM account full access is sufficient to allow the backup to proceed, along with the actual user account you want to use for the backup. – Triynko Dec 15 '14 at 23:26

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by adding system with full permissions it looks like the issue is solved.

Well I guess I'm not giving up that license for Acronis just yet...