Time Machine couldn't complete backup.

[Rod]

Just bought an M2 Pro Mac Mini. Fresh install of Sequoia 15.1, copied my data over, and Time Machine is immediately giving me this exact same error.

I miss Mojave already. Had zero issues with that OS.

eicca, unless you have encrypted your new mini, and that's easy to do unintentially at setup, my suggestion is the same method I have always used for TM backup problems; erase and reformat your external backup and start afresh. Alternatively buy a new dedicated EHD (External Hard Drive) for your new Mini. On connecting it you will be asked if you want to use it for TM and clicking Yes will format the EHD appropriately for TM and choose it for your backups.

Having said that, I have been using the same EHD for my TM backups for years on both Intel and now Silicon MacBook Pros's but I do erase and reformat yearly.

 

[eicca]

eicca, unless you have encrypted your new mini, and that's easy to do unintentially at setup, my suggestion is the same method I have always used for TM backup problems; erase and reformat your external backup and start afresh. Alternatively buy a new dedicated EHD (External Hard Drive) for your new Mini. On connecting it you will be asked if you want to use it for TM and clicking Yes will format the EHD appropriately for TM and choose it for your backups.

Having said that, I have been using the same EHD for my TM backups for years on both Intel and now Silicon MacBook Pros's but I do erase and reformat yearly.

I did start with a fresh blank drive for TM, as I do every time I upgrade computers.

Still got errors almost immediately.

 

[Rod]

Hmm, perhaps, the attached search results in post #60 might hold some answers. Here it is again; Sequoia 15.1 Time Machine couldn't complete backup - Google Search

 

[Rod]

eicca, reading this Apple Community post Time Machine backup on macOS Sequoia cann… - Apple Community does seem to indicate that the Sleep setting may be an issue. I never allow my devices to sleep so that may be worth trying.
Under Battery in settings go to options and check Prevent Automatic Sleeping is ON.

 

[Rod]

Still got errors almost immediately.

What errors did you get?

 

[eicca]

eicca, reading this Apple Community post Time Machine backup on macOS Sequoia cann… - Apple Community does seem to indicate that the Sleep setting may be an issue. I never allow my devices to sleep so that may be worth trying.
Under Battery in settings go to options and check Prevent Automatic Sleeping is ON. View attachment 39858

I’ve already enabled that setting as a workaround to another appalling bug Apple has introduced:

if the computer goes to sleep, the external drives start spinning up and down in 30-second cycles endlessly.

So preventing sleep stopped my drives from being burned up, but didn’t help my Time Machine issues.

 

[eicca]

What errors did you get?

“Time Machine could not complete backup. Will finish when Mac is unlocked” or whatever the verbiage is.

 

[IWT]

“Time Machine could not complete backup. Will finish when Mac is unlocked” or whatever the verbiage is.

These are the settings you need to make within System Settings:



That should allow Time Machine to continue its business uninterupted.

Please confirm these settings and let us Know if TM works or not.

Ian

 

[eicca]

These are the settings you need to make within System Settings:

View attachment 39859

That should allow Time Machine to continue its business uninterupted.

Please confirm these settings and let us Know if TM works or not.

Ian

As stated before, I already tried those, did not fix the issue.

 

[IWT]

As stated before, I already tried those, did not fix the issue.

I beg your pardon. I was unaware that you had tried this and found it wanting. Couldn't find that item.

Ian

 

[Rod]

The error definitely implies that the Mac is or was locked during backup. Ian's Energy settings are different to mine as I have a laptop so my screenshot does not include the, "Put hard disks to sleep when possible" setting.
So, does the backup complete when the system is "awake" or not?

Lastly did you reboot after making the aforementioned changes to your Energy settings?

PS. From what I can find out online all Mac Minis from the Intel to current Mx models are configured for the fans to run all the time, but silently, if they are noisy you should return it to Apple asap before the warrenty expires.

I have an M1 14" MBP with two fans and even at 6000 rpm they are virtually inaudible.

 

[MacInWin]

whatever the verbiage is.

That is the critical information. What exactly is the verbiage?

 

[rbpeirce]

15.1.1 seems to have corrected this on my machine. I am trying to do daily backups to two drives and the last couple have worked and done only one a day as hoped.

 

[rbpeirce]

15.1.1 seems to have corrected this on my machine. I am trying to do daily backups to two drives and the last couple have worked and done only one a day as hoped.

I spoke too soon. It failed again this morning.

 

[rbpeirce]

Let me bounce this off of you. I do a daily backup to two drives. The idea is a backup to one drive today, the other tomorrow, and so on. When I get a failure to backup for today it always seems to be because I already have one. Is it possible or likely that TM recognizes this and knows it doesn't have to do another? If so, why the weird error message? Why doesn't it just silently abort?

 

[MacInWin]

When I get a failure to backup for today it always seems to be because I already have one.

What makes you think that? That is NOT how TM works. Are you getting some message to that effect?

Is it possible or likely that TM recognizes this and knows it doesn't have to do another?

Files change, even when the machine is idle. The system is constantly changing things as part of maintenance and operation. Even with TM set to the default hourly update, there will be changes EVERY hour. So, the answer is a clear "no" to that question.

If so, why the weird error message? Why doesn't it just silently abort?

The error message is trying to tell you that a file TM thinks needs backing up is not available at the time of the backup. That is the sole issue.

TM does not "silently abort." It completes or fails. Completion is silent, any and all failures generate error messages.

This thread is very long so I don't know if you have been told to try The Time Machine Mechanic (T2M2) from eclecticlight.co ( XProCheck, T2M2, Ulbow, Consolation and log utilities ) It's free and good.

Your first post said:

I've just started to encounter this since upgrading to Sequoia. If I'm logged off or asleep it may not complete. If I restart it, it does. I think there may be a setting that causes the machine to wake up for backups but I don't recall what it is.

I didn't read all of the posts, but I did a quick skim and didn't see any exact post with the error message you are getting. My recommendation is to NOT log off, just let the machine go to sleep to see if that is the issue. In the morning, you open the case, or press a key and it wakes up. Mine makes backups overnight just fine with me logged on but asleep.

 

[rbpeirce]

What makes you think that? That is NOT how TM works. Are you getting some message to that effect?

Observation. It doesn't fail to do one backup a day. It does fail to do two.

Files change, even when the machine is idle. The system is constantly changing things as part of maintenance and operation. Even with TM set to the default hourly update, there will be changes EVERY hour. So, the answer is a clear "no" to that question.

Not the point. I was wondering if TM, in its checking process, might notice the daily backup had already been done today so a second one would not be called for. If so no message would be necessary and the message given could be wrong. The number of files that changes would be irrelevant.

The error message is trying to tell you that a file TM thinks needs backing up is not available at the time of the backup. That is the sole issue.

I know. That's why I wondered if the error message might be wrong.

TM does not "silently abort." It completes or fails. Completion is silent, any and all failures generate error messages.

Or doesn't try to do it at all, in which case silence would be nice.

 

[MacInWin]

You said in post #75:

I do a daily backup to two drives. The idea is a backup to one drive today, the other tomorrow, and so on.

Now you are saying something different. So which is it? My comment was based on what you originally said.

Also, I looked back over the thread and you have never said what the error message you are seeing is. What is it, exactly? When you first posted in #44, you said

I've just started to encounter this since upgrading to Sequoia. If I'm logged off or asleep it may not complete. If I restart it, it does. I think there may be a setting that causes the machine to wake up for backups but I don't recall what it is.

From the wording, you are saying that just like the OP, you are getting an error about TM not finishing. The OP said, in part

Every morning my wife's iMac tells her:
Time Machine couldn't complete the backkup to "LACIE Time Machine"
Time machine did not finish baking up because some files were unavailable. Backkups will resume when your Mac is unlocked.

Is that the message your are seeing, or is it something else altogether.

If you have TM set to one backup a day, having two drives to alternate will NOT make two backups in one day, but alternate between days. So you get a backup, for example, to drive 1 on Monday, drive 2 on Tuesday, drive 1 again on Wednesday, and so on. Not two backups in one day to two drives. TM does not work that way at all. What you want is to make two backups on Monday, one to Drive 1 and one to Drive 2. TM won't do that.

But tell us that error message so we can deal with that issue.

 

[rbpeirce]

If you have TM set to one backup a day, having two drives to alternate will NOT make two backups in one day, but alternate between days.

That's the goal and that's what I often end up with except TM will sometimes try to do two backups in one day and produces a message that it couldn't complete the second backup because some files could not be accessed. I've come to think it should abort and produce no error message in this case.

But tell us that error message so we can deal with that issue.

The error message, to the best of my recollection, is that the backup could not complete because some files could not be accessed.

 

[MacInWin]

It is impossible to set TM to make two backups at the same time to two different drives, as I have already described. If you use a third party scheduler for TM, something like Time Machine Editor, for example, it may be possible to have two back-to-back backups, and if those two execute too close in time, TM may not be finished marking the files from the first backup before the second starts. TM runs at low priority, so it can take a few minutes for the "paperwork" to be finished.

Are you using some third-party to try to schedule TM outside of TM's own scheduler?

Your goal is not achievable using just TM.

Without the exact error message, this discussion cannot proceed. Good luck with it.