What causes Time Machine to stall during backups?

I just added the M4 Mac mini to my NAS backups and I am getting the same issue with 15.2. Tried all the solutions here and the issue comes right back. I have a M2 MacBook Air that uses TM to the same NAS and it has no issues, settings are the same so not sure what the issue is. Backups are too important for me, unless Apple fixes this issue I'm going to be using an alternative to TM (most likely Arq) just to much time wasted trying to work around these issues. Starting to feel like a windows user.

I've given up on Time Machine. Far too many problems over the years. I've lost all my history three times so far. After upgrading from macOS 14.7 to 15.2 Time Machine started failing. It would stall/fail during the night trying to complete a backup. No idea why, no idea how to fix it.

Then Time Machine deleted over two years of history! Now that everything is lost (again), I reformatted and tried with a clean drive. Again, failed during the nightly backup. This happened two years ago, and then I lost about three years of history.

Sure, clicking "backup now" would complete a backup but here's the question: How do you know it really worked? Have you tried to to restore? Even when it completed the backup I find many errors in the logs. I find the same errors many other have reported with macOS 15.

So...I do not trust Time Machine, and after so many years of losing backup history I'm done forever.

Now I'm using Carbon Copy Cloner to create backups. Works really well, twice as fast, and does everything Time Machine ever promised and much more.

with your experience, i can't say that i blame you for not trusting the backup. however, every time i've needed to recover a file or file system, the backup was there. now you've got me scared. thanks for nothing :-) (that's supposed to be a smiley face). after taking part in this discussion, i'm going to have an alternate backup system ready to go.

Hi bruiselle! I wanted to report back on my experience directly plugging my two backup HDD into the M4 Mac Mini. Since I already have used two of the Thunderbolt 4 ports in the back of the Mini, I could only plug one of the backup drives into the back of the Mini. I plugged the other backup HDD to one of the 3.1 USB ports in the front of the Mini. I woke up this morning to failure again. I am going to try one more thing. I removed the backup HDD that was connected to the front of the Mini and also removed it from the list of backup drives for TM. So now I have only one backup TM drive and it's connected to the back of the Mini via a Thunderbolt 4 port. Let's see if this works. I prefer two backup drives, but if this works, I'll go with it as I also use Dropbox and Sync for all my documents, etc. BTW, when you said you solved the problem by directly plugging your backup drive(s) into the Mini did you mean using the Thunderbolt ports in the back?

I'm reposting the following comment for historical purposes as it was accidentally deleted by the moderators due to a miscommunication. It was originally Posted on December 29th.

Hi Folks, I bought my wife an M4 Mac mini for Christmas and have it all set up. As for background, I set it up from scratch as a new machine. It is running MacOS 15.2. In general, the new Mini is running fine. Unfortunately, she has the problem discussed in this thread. Time Machine backups cannot be completed...blah, blah, blah. Sometimes, the TM backup continues and finishes on its own once she starts to use the Mac Mini. Sometimes it doesn't and the solution is to click on "Back up now" in TM. After a couple seconds, the backup completes. I am using two external HDD as her TM Drives connected to a CalDigit Element Thunderbolt 4/USB 4 Hub. After reading through this thread, my conclusion is that there is no consistent, solid solution to this problem yet. True? Because of that, and since the "fix" for my wife's Mac mini is to simply click "Back up now" to finish the backups, I am reluctant to try all the suggested solutions only to have the problem remain. From those of you who have spent far more time on the issue, do you feel this is the most reasonable way for me to address the problem and hope that Apple eventually decides this issue is worth their time to fix? BTW, I also have a 2018 Intel Mac Mini. No problems with TM backups to its two external HDD formatted as APFS (just like the new Mac mini). It is also running MacOS 15.2.

I also have a Mac Mini M4, a MacBook Air, and an M1 mini and Time Machine (Sequaoia 15.2) used to have the problems mentioned in this thread, but I did something suggested in the thread and it fixed it. Unfortuately I can't remember what it was but it was on this thread.

Hi bruiselle, Sadly, just connecting one backup HDD to one of the Thunderbolt 4 ports in the back of the Mini did not solve the problem. So, for me, directly connecting the backup hard drives to the Mini is not a solution. I could switch to Carbon Copy Cloner, but I really don't need its extensive functionality and it seems a shame to pay for a pretty expensive application to solve this problem. CCC is usually set to backup once a day and what I may do is steal that idea and apply it to TM for now. Instead of backing up every hour (not really necessary in my case) I think I will set it to back up "Everyday" and when I am usually on my computer. (I assume it sets the time of the day when it will backup to the time the user initiates the "Everyday" option.) This will hopefully mitigate the annoyance of manually using "Back up Now" because the problem only occurs when the Mini is locked. The good news is I have all the ports on my Mini back. Since there was no difference in performance between direct connection to the Mini and connecting my backup drives to my CalDigit Thunderbolt Element hub, I reconnected the two backup hard drives to the Element hub. Thanks so much for going along with me on this adventure and trying to help.

hello mr. luigi. my displays arrive shortly so i started to disassemble my computer and peripherals including the backup drive. i feel like i got very lucky. my usb passport drive is plugged into the usb port on my 2023 m2 mini. this is sad because i shouldn't have to be lucky to have a consistent and positive backup experience. i spent more than a minute or two getting set up to make my backup drive a network drive. i'm off the hook for the nonce. however, i verify the backup every day because i use the recovery feature at least once a week. i hope apple sees this discussion string and fixes the issue as soon as possible. good luck. i'll still be following this discussion.

Hi bruiselee 13! This looks very cool! Thank you for sharing. And I hope you enjoy your new monitors!!! If my guess at when TM schedules my daily backups is wrong, I will check this out. BTW, maybe it's just my computer, but the posts in this discussion thread are chronologically all over the place. Your December 30th post about "timemachineeditor" was put on page 2 of this 6 page discussion. The next post is from Nov. 3rd! Maybe I have some setting all janked up. But if not, something crazy is going on here. Perhaps the discussion about Time Machine has morphed into one about Time TRAVEL. 😂

Hi bruiselee 13, Another update to my situation. I mentioned not wanting to pay for a different backup solution even though TM has gone rogue. Then I remembered I bought a copy of Carbon Copy Cloner for a very specific purpose years ago. Turns out it was CCC version 5 and CCC offers a 50% discount to folks who bought that version when purchasing the most recent version (CCC 7). So I said, "What the ****" and bought CCC7 at a discount. It's now installed on my wife's new M4 Mac Mini and set to backup every hour. Hopefully, this will be the most sane solution to this crazy issue. I am still using one of my drives as a TM drive set to backup once a day. All are connected to my(her) CalDigit Thunderbolt Element Hub.

Regarding Time Machine HD issue. I have now 3 week the Apple Mac mini M4 and trouble with Time Machine. I have tested some ssd HD. Not really any chance, that the Time Machine is working longer without trouble.

My solution is to use a Standard HD like this e.g. Toshiba Canvio Basics 1 TB. This is a mechanical HD. And I have used a USB C to USB A adapter. Now the TimeMachine is working two weeks without any problems. Ok, the HD is not the fastest. Cheers, Thomas

Since the dating of this discussion is all over the place on my Mac, I will start off by saying I am posting this on Jan. 1st. I previously posted that I had a license for Carbon Copy Cloner 5. I stopped using CCC 5 a while ago as I didn't really need its extensive functionality. However, after all the hassles I have had with TM and my M4 Mac Mini I decided to revisit the CCC website. Happily found out yesterday that I qualified for a discount on the latest version of Carbon Copy Cloner 7 because I had paid for CCC 5. So I bought CCC 7 for a very reasonable price of about $30. I installed it on my Mac mini and set it to back up every hour on the hour. That was 24 backups ago and CCC 7 has worked flawlessly. IMO, the money spent is well worth not having the hassles of TM. Clearly, Bombich software, who makes Carbon Copy Cloner is putting more effort into their product than Apple is with TM. As an experiment, I kept my 2nd backup hardrive connected to TM but set it to back up every "hour + 1 minute on the hour + 1 minute." So 5:01, 6:01, etc. Because CCC 7 initiated a backup at 5:00, 6:00, etc. the TM backups scheduled for 1 minute later ARE ALL PROCEEDING nicely. No more failed backups. At least for one day. If things stay as they presently are, I will continue to dedicate one of my backup harddrives to CCC 7 and one to TM. If TM starts to get naughty again, I am going to abandon TM completely and use CCC 7 on both my backup harddrives. I hope my experience is of help to some of you. I remember when I got my 2018 Mac Mini, the "Unlock my Mac via Apple Watch" feature performed very poorly despite many folks having the same problem. To this day it continues to perform poorly. So I don't hold out any hope that Apple will fix TM with our Macs and refuse to be jerked around anymore by the problem. I consider the $30 spend on CCC a great investment in performance and sanity.

Update: My success backing up using Carbon Copy Cloner for one drive and TM for another with the TM backups set to proceed 1 minute after the CCC backups was short lived. The TM backups reverted to their old, "Can't complete the backup...blah, blah, blah" message a day later.

So, I have totally abandoned TM as a backup tool and now use Carbon Copy Cloner 7 for both of my backup drives and it performs perfectly. As I said in a previous message, I hold out no hope that Apple will solve this problem and consider the $30 spent to update my version of CCC well worth the money in terms of performance and peace of mind.

hi mr. luigi. i've read all of your postings, but i'm just going to respond to this one. ccc sounds like a good solution and i'm going to keep it in mind if/when my backups start failing again. as for this group's timeline? i see the same sort of page/response arrangement. it looks like they're using a scatter algorithm to "sort" the responses. finally, my two displays work great except another problem re-reared its head. (this was a problem that i believe was fixed and is once again broken.) when the displays wake up from being asleep, all the windows migrate to the primary display. so i have to drag them all back. i wrote a black screen saver and never allow my displays to sleep. sad. oh, i have six workspaces spread over the two displays. lots of fun.

Hi bruiselee, old friend!

Sorry to hear about your displays. I have two 4K displays in my setup and sometimes when I log-in the main display fails to "activate." I have to unplug its connector to my 2018 Mac Mini and plug it back in and that solves the problem. Other times the screens that were on one monitor reappear on the other monitor when I log in and the secondary display becomes the main display. This doesn't happen often, so I just live with it. But I thought I would mention it since you shared your own experience with your displays. CCC continues to perform like a dream. It is such a relief to not have to deal with TM backup problems anymore. Especially since the M4 Mac Mini that has the problem was a Christmas Present from me to my wife and I wanted her to have a fun and smooth experience with her new machine. The last thing I wanted was for her to have me constantly on HER Mini trying to solve the TM issue. As I read the posts here about the problems people continue to have with TM, it makes me wish I was infinitely wealthy so I could gift them a license to Carbon Copy Cloner so they could be done with the problem and enjoy their computers. Too bad CCC hasn't seen this discussion thread. If they had, I think it would be smart business for them to offer everyone a discount to CCC 7 using the coupon code, "TimeMachineWillDriveYouMad." 🤣🤣🤣 Cheers, Luigi