Time Machine - an error occurred while preparing the backup

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Level 1

9 points

Time Machine - an error occurred while preparing the backup

I use an external drive so I can backup my MacBook Pro using Time Machine. It is configured and Time Machine has been successfully backing up my folders. But since yesterday every time Time Machine starts preparing the backup it encounters an error. The only message I get is 'Time Machine couldn't complete the backup to [external drive name] - An error occurred while preparing the backup'.

I tried ejecting the external drive and reconnecting it but I get the same problem. I tried rebooting my laptop and start over, but I still get the same problem.

Has anyone had this problem? How can I fix it?

MacBook Pro with Touch Bar

Posted on Dec 25, 2020 4:41 AM

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Answer 1

Top-ranking reply

karina184

Community Specialist

Dec 27, 2020 7:23 AM in response to mohd.shafiee

Hello mohd.shafiee,

Thanks for using the Apple Support Communities. We understand you're having an issue backing up your MacBook with Time Machine. If you haven't done so yet, check out article, If you can't back up or restore your Mac using Time Machine. The 3rd bullet point here might be the best option to address this issue.

Best regards.

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Answer 2

ArtyYeo

Level 1

22 points

Feb 1, 2021 8:30 AM in response to mohd.shafiee

I'm having the exact issue with my MacMini using BigSur 11.1

See my thread ... I have tried many things, including getting a new HD and it's still happening.

https://discussions.apple.com/thread/252341987

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Answer 3

mohd.shafiee Author

Level 1

9 points

Dec 27, 2020 12:05 PM in response to karina184

Hello Karina,

Thanks for the advice. Before receiving your response I actually did some of the steps mentioned in the article in the link you gave me. In the end I had to resort to erasing the hard disk and reconfiguring it for Time Machine and its working fine now. I'm not happy though that I lost my backups but glad that its working fine now.

Best regards.

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Answer 4

Feb 1, 2021 1:51 PM in response to ArtyYeo

I have the same problem. In my case I am using two external hard drives, connected via USB 3.0 ports to USB C laptop ports. MacBook Pro (2019), Big Sur 11.1, 4TB internal SSD. BU drives were formatted APFS about 3 months ago, and I have made 3 successful TM backups since. Today all backup attempts fail, separately to both drives. I can't see that anything significant changed since backups were successful. Time Machine Mechanic displays logs that end with:

2021-02-01 14:08:22.638867-0500 Backup failed (303: BACKUP_FAILED_PREFLIGHT_STAGE_GATHER_EVENTS)

I have run disk first aid on the external and internal drives. Looking at the error message, and since it started failing on both external drives at once, to me it seems to be an issue on the laptop, not the external drives.

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