Timemachine Back-up in MacOS 26 (Tahoe) does not work on Synology DS920+ NAS

I have two NAS, one Synology and one QNAP, and after installing Tahoe both time machine backups stopped working. Time machine says that the backup location is unavailable after a short while. I have not touched any configuration. Deleting old backups makes no difference. Tahoe is broken

Aha, unfortunately I cannot offer any other advice, I am not an IT expert. I consulted this problem with Apple and Synology and after sending logs from the NAS I received this response from Synology. Your problem is probably somewhere else. I recommend contacting Synology – I believe you have a DS224+ as you wrote, you will have to get through AI to a live technician who will guide you on how to send logs from the NAS. Once you upload them to Synology support, within about 3 days the logs are reviewed and they will send a solution. I have had a good experience with Synology. Unfortunately, I do not have any other immediate advice… I am sorry… I am a lawyer and IT is just my user hobby xD

I have the same problem as everyone else. Changing all characters in folder and file names from Swedish to English didn't make any difference. I've also tried the proposed solution from karel250 but that didn't make any difference. A solution that worked was changing the Mac's preferred language from Swedish to English. A one time solution that won't work in the long run. I suppose that developers in California only test with their native language

Thank you. Backups finally working again. Problem was Záloha (translated Backup) in image name / description or whatever it is.

Also on the previous version of MacOS I had problems using my Synology for Time Machine backups. My MacBookPro M1 would loose connection to the NAS every time it came back from sleep. I fixed this installing Automounter, since then I had no problems. Until Tahoe.....

In order to have Time Machine backups with Tahoe on my Synology I had to start from scratch...

I’m experiencing the same issue – Time Machine shows the following error: “Time Machine can’t complete the backup to ‘Time Machine’. The backup disk is not available. Make sure it is connected or select a different backup disk.”

Regular connection to the NAS disk over the network works fine. However, after the update, direct access to the NAS via the Finder sidebar (where I had created a shortcut pointing directly to a specific folder on the NAS) also stopped working, even though it used to work before. Creating a completely new backup on a new disk on my Synology NAS (DS418) did not help either.

After I updated to Tahoe, TimeMachine started to backup on the NAS On the existing AFP share, but stopped. After restarting it stopped again.

Then I deleted the existing Back-up and I configured the NAS as required with SMB.

Now I get the login errors.

The other Shared folders are only accessible when I configure AFP again.

As workaround I have my personal data files stored on iCloud-drive.

Besides my Synology DS224+ NAS unit, I also installed one Unifi UNAS2 NAS unit, but experience exactly the same result, it doesn´t work with MacOS 26 computers. Earlier MacOS computers work just fine with the Time Machine.

I tried following the instructions on the DS 120J, which I use just for storing backups, but it still doesn't work. It transfers the profile, starts up, and then immediately stops with an error saying that the disk has been disconnected. Which is nonsense because I can see it in Finder. I have an exception in my firewall and everything is OK. The update just somehow ruined the whole Time Machine.

Time machine stopped backing up to my NAS DS423, the 15/9, the same day i updated to MacOs 26. Before that date backup worked like clock. I´ve been through all loops and hoops I can think of to no avail.

I have other software like Lightroom that flawlessly backup to my NAS and software that uses the NAS for different purposes.

Whatever I do all i get is the message that ”DS423.local is not available”. I can mount the backup folder in TM without problem but after few seconds after the backup have started i get thar error message

It works! I tried it on Synology without encryption for now, Thank you very much

Look in this thread and under my username for the solution – I posted an exact guide for your problem.

Thanks for your answer. I did reboot the DS920+ and it did not work.

Next try was to kill AFP and tested it again. Now the DS902Plus share is shown in Network and Finder, but an error was shown. IP-adres not available or something.

On my iPhone and iPad I can login at the NAS and I can access shares and files, but on MacOS Tahoe I still get no permission.

The Synology-assistent.app shows the Root Share DS920Plus and redirects via Safari to the Webportal, on which I can login.

Can you post the link to this kansen article, because I’m not sure I have configured the setting right.

Now I have SMB only and AFP disabled and the Share is shown up.

Finder and TimeMachine does not find the IP-Adress for DS920Plus.

willem-blues wrote:

Can you post the link to this kansen article, because I’m not sure I have configured the setting right.

Now I have SMB only and AFP disabled and the Share is shown up.

Finder and TimeMachine does not find the IP-Adress for DS920Plus.

I used the same article as the link in your original post. If it helps, here are my settings for the NAS.

[Edited by Moderator]