# IMac backup fails on WD My Book

**URL:** <https://forums.sandisk.com/t/imac-backup-fails-on-wd-my-book/401569>\
**Category:** External SSD for macOS\
**Created:** [June 6, 2021, 4:48pm UTC](https://forums.sandisk.com/t/imac-backup-fails-on-wd-my-book/401569 "2021-06-06T16:48:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![AndreaBeddies](https://avatars.discourse-cdn.com/v4/letter/a/a698b9/32.png) [@AndreaBeddies](https://forums.sandisk.com/u/AndreaBeddies)\
**Post date:** [June 6, 2021, 4:48pm UTC](https://forums.sandisk.com/t/imac-backup-fails-on-wd-my-book/401569/1 "2021-06-06T16:48:39Z")

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Unfortunately I can’t backup my files on “My Book”. The following error message is shown:

Time Machine couldn’t complete the backup on “My Book”: The backup disk is not in MAC OS Extended (Journaled) format, wich is required.

It would be grat if somebody could help me.  
Best regards

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**Author:** ![DonaldKepler](https://sea2.discourse-cdn.com/sandisk/user_avatar/forums.sandisk.com/donaldkepler/32/54344_2.png) [@DonaldKepler](https://forums.sandisk.com/u/DonaldKepler)\
**Post date:** [June 8, 2021, 8:10am UTC](https://forums.sandisk.com/t/imac-backup-fails-on-wd-my-book/401569/2 "2021-06-08T08:10:52Z")

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Erase your external hard drive with MacOS Journaled and tryagain.