My Book Duo 16TB on Mojave: error with Time Machine when computer goes in sleep mode


we have attached a brand new 16TB unit to an iMac running Mojave. When the system goes in sleep mode, it seems Time Machine is unable to keep on backing up on the device. We receive this error:

“Time Machine couldn’t complete the backup. Unable to complete backup. An error occurred while creating the backup folder”.

Additionally, if we try to access the backup drive, it looks completely empty in Finder (even though the space usage is still correct) until we eject it or do a system reboot. Once again, this after after sleep mode.

A few notes:

  • We already disabled Sleep Mode in WD Drive Utilities (latest version)
  • We have Power Nap enabled in Mojave
  • There is another Duo Drive (8TB) attached to the machine but not being used for Time Machine, which was working fine when the computer came back from sleep. So I suppose the error is a mix of Time Machine running on WD drives.

We saw the issue recurs in many other topics here and also on other websites, like reddit. What should we do?


Hi magneticat,

Time Machine backup failed or could not complete… error would appear when the computer enters into sleep mode during the Time Machine backup as this makes destination disk unavailable.

You should try to check after adjusting the macOS System Preferences – Energy Saver settings prevent the computer from entering sleep, keep the hard drives awake. You can have a look on below article for more details about this concern.

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Thank you Brandon, I had found that support guide already and so far it seems to be working. I will let you know if it fails again.