Why is Time Machine getting stuck partway through backups?

I was having the same problem. I tried disc first aid (no issues). I tried to reformat my external drive. I bought a new external drive. I tried different formatting types (APFS, APFS Case Sensitive, etc.) Nothing seemed to work. The backup would always stall midway through.

What fixed it for me is I went through different folders and started excluding them from Time Machine, until I finally excluded the Google Drive folder. After excluding the Google Drive folder the backup works fine. I'm not sure if it's Google Drive specific, or if it may be a problem with other syncing services that stream files as well. I have Dropbox and iCloud and both of those work fine with Time Machine backup, so I'm not sure.

So definitely try excluding any file syncing folders, especially the Google Drive folder, if you're having the same problem. It worked for me.

I'm having the same Time Machine issue after upgrading to Sonomo. Right now the message is:

59.9% done - About 11 hours remaining 1.84GB compied. 10 hours ago the message was nearly identical. And 10 hours before nearly the same. I had earlier cancelled the backup after having this same problem. But it's happening again. I doubt it will ever finish. I have yet to complete a Time Machine backup after upgrading to Sonomo.

I had the same problem after upgrading to Sonoma (14.1.1). Time Machine backups would stall part way through and just never finish. I never figured out what was causing the problem, but I solved it by formatting a new disk as APFS and designating it as the Time Machine backup destination. Starting over with a freshly-formatted APFS disk solved the problem.

I think I have found the problem. My external G drive has a USBC connector. I had been using the drive for TimeMachine without problems by connecting to the Mac with the cable provided by the disk drive maker. But recently I began using a new USBC - USBC cable. I changed cables because my MacBook has spare USBC ports. So I moved the drive from my USB hub to a direct USBC connection to the Mac. Since then, I've experienced the erratic behavior of TimeMachine that is described in this forum. On a hunch, I changed back to the original cable and when the drive mounted, I opened it and deleted the partial file that was on the disk. TimeMachine now works properly. I suspect that the problem was caused because USBC is a new standard that provides variable power. My old G drive was expecting 5 volts. The Mac may be delivering the wrong voltage to the drive.

I'm having this problem too. Time Machine gets stuck partway through the backup process and crawls to a halt. It's inconsistent.... sometimes if I let it run overnight it completes. Another time it ran for 24 hours and never completed. I followed the suggestion made here and reformatted my external backup disk and eventually the first backup completed. Now the second backup to this drive has been at 72.5 percent done, 291.2 mb copied for two hours.

Note: I use two backup drives: One is Thunderbolt and the other is USB3. Both are formatted AFPS and marked as "Time Machine" volumes. This issue appears with both backup drives. I'm running the latest version of Sonoma. This started, I believe, when I upgraded to 14.1. The computer is an M1 Mac mini, 2020.

Oddly enough, I am NOT encountering this problem with either of my other two Macs (M2 Max Studio and M1 Max MacBook Pro). Under Sonoma 14.1 with both local USB or Thunderbolt drives and remote NAS storage Time Machine works just fine.

I'm totally at a loss. In the meantime until a fix is resolved, I've made a full system backup to an SSD using Carbon Copy Cloner.

I've been having the same issue, with backups getting stalled for hours, though they would finally finish if I let them go. The latest MacOS update (Sonoma 14.2) didn't fix it, but erasing and reformatting my backup disk did. After the first full backup, which took a long time, of course, hourly incremental backups are running normally again. They finish in minutes instead of hours. I don't know if it matters, but I reformatted with APFS (Case-sensitive, encrypted), which it wasn't before.

Same problem. Backup recently started freezing at around 33% done (4.5 GB), no matter how long I waited for it progress further. (No changes to cables used. Upgraded to Sonoma a few months ago.)

I reformatted the backup drive APFS, and the new backup completed without incident.

I wish I had run a Disk Utility scan before wiping it, just to see if there was a clue there. It's a fairly new drive but I will have to keep a close eye on it.

nosnetrom wrote:

I just upgraded to Sonoma 14.0 in the last couple days. Yesterday I started running a Time Machine backup that got to 64% complete, then was stuck for hours;

I finally selected to skip the backup.

I started another backup last night, now, about 14 hours later, it's stuck at 82% complete (7.00GB copied). What could be the problem? (FWIW, last night I reset backups to run daily instead of hourly.) Thanks in advance!

I would let it run and see if it will finish.

If the issue continues, a Time Machine that will not complete is one indication of a failing drive

others would be:

“failed to complete the backup ”

"Time Machine has completed a new backup for you"

"it can't create the backup,"

“Preparing backup”

If any of these message appear repeatedly —the Time Machine drive is operating in a state of failure.

The resolve would be to replace the drive.

Time Machine troubleshooting on Mac

Time Machine troubleshooting on Mac - Apple Support

If you value your user data

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

More than one device, more than one backup methodology.

I have the same problem on Sonoma 14.1.1 (23B81) my network time machine backup gets stuck at 10%. I didn't have this problem on Ventura.

I have a MacBook Pro M2 13" and have almost the identical problem since upgrading to Sonoma 14.1 although I let it run for 14 hours the other day and it finally finished a backup. Still taking around 10-12 hours to complete new backups which was the case today. Before upgrading to Sonoma it used to take no more than 20-40 mins most. I hate leaving my computer plugged in for hours as we all know it's not good for battery life. I called apple support and they have no answer. Hopefully they figure it out with the next update.

Same issue here, hoping it'll resolve itself so I don't lose the previous backup but it's not looking good based on all of these comments before mine. I appreciate everyone who's posted about this. I might let it run another 24 hours and see what happens I suppose.

I have a similar problem: I would get a message "Couldn't backup file....". I restarted the backup process a couple of times and it finished it in the end (just click Backup Now).

This happened immediately after I upgraded to Sonoma 14.1.2.

I hope Apple guys fix this problem.

Depends, I tend to think APFS was made for Macs with internal SSD or NVMA drives internal ONLY! Ever sense the release over the last few years traction platter drives started failing quicker than normal! So I urge with traditional DAS drives use the older HFS+ because at this point Time Machine still sees that format!