Windows Server 2012 r2 Backup Error 0x807800C5

Question

The backup operation that started at '‎2021‎-‎05‎-‎27T03:30:03.748786100Z' has failed with following error code '0x807800C5' (There was a failure in preparing the backup image of one of the volumes in the backup set.). Please review the event details for a solution, and then rerun the backup operation once the issue is resolved.

From the Log:

Backup of volume \?\GLOBALROOT\Device\HarddiskVolume2\ has failed. The semaphore timeout period has expired.

have deleted all the unknown devices, deleted the generic shadow volume copies, assigned a letter to recovery and changed the size. but still keep getting this error.

it fails when at the EFI and system state parts of the backup

Answer 1

Hi,

Thanks for posting on our forum!

Have you renamed the old backup folder? Because preparing the backup image failed with error code 0x807800c5 suggests a conflict of the identical folders named WindowsImageBackup.

In addition, according to your event log, you can try these tips first:

https://www.auslogics.com/en/articles/remove-semaphore-timeout-period-has-expired/

https://windowsreport.com/fix-semaphore-expired/ (You can put using third-party tool as your last option)

Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.

Please tell me any results after you tried these tips. Thanks for your support!

BR,
Joan

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Answer 2

I am having this same problem with Windows Server 2016 backup. Semaphore timeout on EFI system partition. I made sure there was no previous backup folder first. Fails every time. Does anyone have a solution? Very annoying not being able to backup my server.

Answer 3

Hello,

If this is an external disk, try replacing the disk and running a new full backups to eliminate the possibility of bad backup media.

USB disks are unreliable under heavy use and often get corrupted tracks/sectors which can cause Windows backup to fail.

-Miguel
https://www.falconitservices.com'

Answer 4

Thanks but both the source and destination are internal SATA. Chkdsk reports no errors.

Answer 5

Hello,

I haven't used Windows backup in years so forgive me if I'm rusty but there should be a backup log in TXT in Windows dir somewhere. Is that what you are looking at? That's the only error in the entire log? Can you post the entire log for the failed job?

Try SFC /Scannow or DISM /Online /Cleanup-Image /RestoreHealth to make sure there is no corruption at the source that's causing the timeout because some files cannot be read. This is just my hunch... The snapshot cannot proceed because parts of the source disk cannot be read.

There is ample space on the source disk? If the target disk media a network share, check that the media formatted NTFS. If not files larger than 4Gb cannot be written and may cause the backup to fail.