You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

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

Reply
Question marked as Top-ranking reply

Posted on Dec 27, 2020 7:23 AM

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.

6 replies
Question marked as Top-ranking reply

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.

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.

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.

Time Machine - an error occurred while preparing the backup

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.