Time Machine backups to NAS are not happening automatically

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Level 1

132 points

Time Machine backups to NAS are not happening automatically

Time Machine backup to NAS only runs once. I have a NAS running TrueNAS on my home network. I can have Time Machine do backups to it. The other family members’ Macs have no problems with the backup running on schedule.

Only on my MacBook Pro do the backups not repeat. I can trigger a backup with “Backup Now” from the Time Machine backup. It looks like it completes successfully. However, At some time a while ago these backups quit happening automatically. I don’t know, how to investigate why.

MacBook Pro 16″, macOS 26.3

Posted on Feb 16, 2026 7:49 PM

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Answer 1

Top-ranking reply

Zurarczurx

Level 4

2,972 points

Feb 17, 2026 4:22 AM in response to D. Hoffmann

If that TM is set up correctly as advised in the other pos then problem might be that the NAS is dismounting periodically and then not automatically re-mounting. ]

Open keychain and make sure that there is only one entry for the NAS and password combination. If there are more than one then delete them all, log in to the NAS again, open the TM share and make sure you tick the option to save the password.

If the above is not the issue then go to Finder and in the top menu Go/Connect to Server and connect to the server using its IP address. When it asks you for a password make sure you tick the save password option.

If still not getting anywhere then In TM settings remove the NAS disk as a backup destination. Then re-add it. It should recognize it as a backup of your Mac and ask if you want to use it or start a new one. Just use it. If you've encrypted the backup then you'll need the encryption password as well as the password for the NAS.

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Answer 2

D. Hoffmann Author

Level 1

132 points

Feb 17, 2026 11:17 AM in response to Zurarczurx

Zurarczurx wrote:

If still not getting anywhere then In TM settings remove the NAS disk as a backup destination. Then re-add it. It should recognize it as a backup of your Mac and ask if you want to use it or start a new one. Just use it. If you've encrypted the backup then you'll need the encryption password as well as the password for the NAS.

Well, that did it:

It completed the first automatic backup to the NAS since re-setting it up the backup destination, at 2:09 PM.

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Answer 3

D. Hoffmann Author

Level 1

132 points

Feb 17, 2026 6:46 AM in response to Zurarczurx

Zurarczurx wrote:

Open keychain and make sure that there is only one entry for the NAS and password combination. If there are more than one then delete them all, log in to the NAS again, open the TM share and make sure you tick the option to save the password.

I tried that. It wasn’t that. I am about to try your next suggestion.

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Answer 4

Feb 17, 2026 7:29 AM in response to D. Hoffmann

D. Hoffmann wrote:

I will reboot my NAS and then try again.

I have seen the error in your screenshot once or twice on one of the 5 Macs that back up to the NAS. Rebooting the NAS corrected it.

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Answer 5

Feb 17, 2026 11:22 AM in response to D. Hoffmann

The backup image on the NAS being busy was most likely the problem. That will prevent it from being used to update the backup. Most NAS boxes run internal optimizations periodically, and sometimes the image file does not get flagged as complete. Rebooting the NAS corrects that.

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Answer 6

Feb 16, 2026 9:09 PM in response to D. Hoffmann

In System Settings > General > Time Machine > Options (button), confirm that the Backup Frequency is set to Automatically Every Hour.

FYI, I have a Synology NAS and the hourly TM backups are working fine from 5 Macs in the house, including mine that is on macOS 26.3 (one other Mac is on Tahoe, the rest still on Sequoia).

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Answer 7

D. Hoffmann Author

Level 1

132 points

Feb 17, 2026 6:51 AM in response to Zurarczurx

Zurarczurx wrote:

If still not getting anywhere then In TM settings remove the NAS disk as a backup destination. Then re-add it. It should recognize it as a backup of your Mac and ask if you want to use it or start a new one. Just use it. If you've encrypted the backup then you'll need the encryption password as well as the password for the NAS.

I tried that. This is what I am getting:

I will reboot my NAS and then try again. I am wondering, however, whether this being busy is getting in the way of subsequent hourly backups. If that’s the case, I will have to investigate on the TrueNAS side of things.

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