Time Machine backups deleted from external hard drive

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Time Machine backups deleted from external hard drive

So on October 4th was my last time machine backup from my macbook pro m1. On that same day I traded it in for a macbook air m4. When I booted up the air for the first time I had all my external hard drives attached. I attached the time machine backup drive and selected that as the time machine disk for the air as well. I never finished the initial backup when I saw that instead of seeing my hard drive changed from (my name) macbook pro to (my name) macbook air and all of my backups from June 2025 through October 4th are not present. What happened? I was told by chatgpt to use testdisk, disk drill and DMDE. I spent over 2 days with both testdisk and DMDE and not sure which one anymore but one of them had results showed my daily backups but each day wasn’t a full backup only changes for the day. I am not seeing any results when I go into recovery mode and click restore from time machine. So chatgpt told me to run migrate assistance well the first attempt I saw disk that said .AssetData when clicking on it said selected source cannot be used for migration.

ineligible os x too old. I have installed os 26.0.1 and back on October 4th the last day of backups sadly I am unable to find an .pkg or even the install app for that same version. Instead I see only IPSW which requires using 2 mac’s and apple configuration 2. I don’t own another mac so that’s out of the options. Last resort is to take it to a local recovery store were they will do a free scan to see if they can restore the portable non power based hard drive. Do you think they will have luck and being a time machine hard drive that was formatted to apfs case sensitive. I need my system back up and running I have important documents and apps that I don’t even recall every app that was installed.

[Edited by Moderator]

MacBook Air (M4, 2025)

Posted on Nov 11, 2025 9:39 PM

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Answer 1

Top-ranking reply

iamshivam

Level 2

158 points

Nov 11, 2025 11:27 PM in response to PokemonFan1987

When you connected that old Time Machine drive to your MacBook and selected it as the backup disk, macOS reinitialized the Time Machine structure, effectively overwriting the existing backup history.

Since Time Machine backups are incremental and tightly linked to the specific machine ID (UUID) of the Mac that created them, the new Mac saw your drive as a new system and began preparing a new backup set, which replaced the catalog data linking to your previous ones. The daily “changes only” backups you saw in TestDisk or DMDE were the delta snapshots that rely on that missing catalog, so they appear incomplete. A professional data recovery shop might be able to pull individual .backupbundle or .snapshots from the APFS container, but full Time Machine restoration is unlikely since the index metadata is gone.

If the data is critical, ask the recovery team to do a deep APFS scan and extract files by type rather than trying to restore the Time Machine structure itself.

There are some data recovery software programs as well. If you are unable to visit data recovery services, you can try Stellar Data Recovery Software or PhotoRec Software to get back your backups.

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Answer 2

Nov 12, 2025 4:17 AM in response to PokemonFan1987

When you set up the new Mac, did you use Setup/Migration assistant from either the old Mac or the TM backup of the old Mac (personally, I always do the latter)? If so, after setup when you next connected the TM backup drive you should have seen a prompt to Claim the backups on that drive. If you declined that option, a new set of backups would have been started. The old backups would still be on the drive but you will be unable to browse them. You may be able to delete the drive from the list of TM destinations, disconnect and reconnect the drive and select it, then be able to claim the old backups.

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Answer 3

Barney-15E

Level 10

122,120 points

Nov 12, 2025 5:08 AM in response to neuroanatomist

If you declined that option, a new set of backups would have been started. The old backups would still be on the drive but you will be unable to browse them.

Time Machine no longer works that way. There cannot be two backups on the same volume. If you don’t inherit the backups, it will erase the drive to set up for the new backups. There should be a warning that it will erase all data on the drive.

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Answer 4

Nov 12, 2025 5:12 AM in response to Barney-15E

Thanks for the correction, I have never declined the option to claim the backups.

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