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User profile for user: cnscns
cnscns Author
User level: Level 1
9 points

Why is this Time Machine (Big Sur) failing -- here's the log

After being away a couple of months, my Time Machine can not resume backing up. It is about 1TB of data, it runs forever and fails with "Time Machine did not finish backing up because some files were unavailable. Backups will resume when your Mac is unlocked."


I am running this from an admin account so it should have full access. How can I troubleshoot this?


Here is the end of a log from the most recent failed run:


2021-08-23 12:13:40  Copied 1.38 GB (+ 1.43 GB) of 368.42 GB, 127560 (+ 129529) of 1172439 items (~- MB/s, 6.30 items/s).  Last path seen: /Volumes/Time Machine Backups/Backups.backupdb/XXX MB Air M1/2021-08-23-054229.inProgress/95DFDDC2-17BF-4640-AFE1-1CDA9018DBD2/Data/Applications/Microsoft PowerPoint.app/Contents/Resources/Office Themes/Office Theme.thmx

2021-08-23 12:18:40  FlCp:882 DrCp:121873 SmCp:6359 FlLn:16 FlLnSk:1236093 DrLnSk:17964

2021-08-23 12:18:40  129130 Added (l: 1.33 GB p: 1.36 GB) - 1478030 Propagated (l: 647.13 GB p: 643.21 GB)

2021-08-23 12:18:40  Copied 1.38 GB (+ 1.43 GB) of 368.42 GB, 129130 (+ 129529) of 1172439 items (~- MB/s, 5.23 items/s).  Last path seen: /Volumes/Time Machine Backups/Backups.backupdb/XXX MB Air M1/2021-08-23-054229.inProgress/95DFDDC2-17BF-4640-AFE1-1CDA9018DBD2/Data/Applications/Microsoft PowerPoint.app/Contents/Frameworks/mso99.framework/Versions/A/Resources/OUIHelpViewerBundle.bundle/Contents/Resources/es.lproj/OUIAboutPanel_mac.strings

2021-08-23 12:20:07  Finished copying from volume "Data"

2021-08-23 12:20:07  Interrupted comparisons: Mtch:1259760,MdDte:72948,Ownr:2149,Mde:203,XAttrNme:149,Sz:984

2021-08-23 12:20:11  Found 355 perfect clone families, 1 partial clone families. Shared space 548.4 MB (548382745 bytes).

2021-08-23 12:20:32  Saved clone family cache for 'Data' at /Volumes/Time Machine Backups/Backups.backupdb/XXX MB Air M1/2021-08-23-054229.inProgress/95DFDDC2-17BF-4640-AFE1-1CDA9018DBD2/.29B3EADA-8796-4D07-9CF9-33B8497DB266.clonedb

2021-08-23 12:20:45  Saved back-up-later cache at /Volumes/Time Machine Backups/Backups.backupdb/XXX MB Air M1/2021-08-23-054229.inProgress/95DFDDC2-17BF-4640-AFE1-1CDA9018DBD2/.reservations.plist

2021-08-23 12:20:45  Failed postflight for destination <Destination /Volumes/Time Machine Backups>

2021-08-23 12:20:48  Unmounted local snapshot: com.apple.TimeMachine.2021-08-23-054243.local at path: /Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/XXX MB Air M1/2021-08-23-054243/Data source: Data

2021-08-23 12:21:03  Backup failed (104: BACKUP_DELAYED_UNFINISHED_PROTECTED_FILES)

2021-08-23 12:22:58  Diskmanagement failed to unmount disk '/Volumes/.timemachine/XXXDS416J.local/2587AF7D-BE4E-4C25-B6A5-4DD6306A059D/TimeMachineXXX', error: {

    Target = "file:     Target = "file:///Volumes/.timemachine/XXXDS416J.local/2587AF7D-BE4E-4C25-B6A5-4DD6306A059D/TimeMachineXXX/";

2021-08-23 12:22:58  Failed to unmount '/Volumes/.timemachine/XXXDS416J.local/2587AF7D-BE4E-4C25-B6A5-4DD6306A059D/TimeMachineXXX', error: Error Domain=com.apple.diskmanagement Code=0 "No error" UserInfo={NSDebugDescription=No error, NSLocalizedDescription=No Error.}

2021-08-23 12:22:58  TMPowerState: 0

2021-08-23 12:40:08  TMPowerState: 1

2021-08-23 12:40:18  Computer is on battery power

2021-08-23 12:40:18  TMPowerState: 0

2021-08-23 13:33:10  TMPowerState: 2

2021-08-23 13:33:10  Computer is on battery power

2021-08-23 13:33:10  TMPowerState: 2

XXX-MB-Air:Time Machine Backups XXXadmin$ 

Posted on Aug 23, 2021 1:44 PM

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User profile for user: Tesserax
Tesserax
User level: Level 10
148,583 points

Posted on Aug 24, 2021 7:32 PM

Ok, now that we know you are performing TM backups to a Synology "file server" this rings a bell. If by that you mean a Synology NAS, then I had the same issue with TM backups from my Mac mini (running macOS Big Sur) to my Synology NAS. It had worked perfectly for years and starting causing issues with the later versions of Big Sur. I did not resort to switching to AFP, but continue to use SMB connections. What resolved this for me was to update the NAS to the very latest version of DSM. Once I did that TM starting working again. May be worth a try for you.

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User profile for user: Tesserax
Tesserax
User level: Level 10
148,583 points

Aug 24, 2021 7:32 PM in response to cnscns

Ok, now that we know you are performing TM backups to a Synology "file server" this rings a bell. If by that you mean a Synology NAS, then I had the same issue with TM backups from my Mac mini (running macOS Big Sur) to my Synology NAS. It had worked perfectly for years and starting causing issues with the later versions of Big Sur. I did not resort to switching to AFP, but continue to use SMB connections. What resolved this for me was to update the NAS to the very latest version of DSM. Once I did that TM starting working again. May be worth a try for you.

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User profile for user: Tesserax
Tesserax
User level: Level 10
148,583 points

Aug 26, 2021 2:46 PM in response to cnscns

Since you seem to be quite adept with logs, I thought I'd share something that you may find helpful for future troubleshooting. Forgive me if you already are aware of the following, just wanted to be sure you knew.


For reviewing macOS logs, i use a number of utilities provided by The Eclectic Light Company. For Time Machine, I find their Mints app perfect for this. To help get acquainted with its functionality, they also provide the following article:


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User profile for user: cnscns
cnscns Author
User level: Level 1
9 points

Aug 24, 2021 8:06 PM in response to Tesserax

Yes, I recall something similar from Big Sur days. This is not so clear as a solution right now. My Synology reports my 6.2.4-25556 as "up to date".


However, it also advertises an option to upgrade to DSM 7.0. But, the release notes for 7.0 caution that performance may be impacted if your server has less than 1GB RAM, and I have 512MB.


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User profile for user: cnscns
cnscns Author
User level: Level 1
9 points

Aug 26, 2021 12:12 PM in response to Tesserax

OK, I rolled the dice and upgraded to DSM 7.0; it seems like the performance issues they were warning about affect services I don't use such as the Photo or Surveillance servers.


But sadly, my TM backup is still hanging after 24 hours, albeit at a different point. The status has hung at "Cleaning Up...", and the abort option has changed to "Skip Cleaning Up". But I have not been able to find out if aborting now will leave me with a complete albeit 'uncleaned up' backup. Logic would say it would as Clean Up is generally defined as deleting now unneeded older backups, but so far little about TM's responses make sense!


tmutil output (unchanging over 24 hours):


Backup session status:
{
  BackupPhase = ThinningPostBackup;
  ClientID = "com.apple.backupd";
  DateOfStateChange = "2021-08-26 00:15:05 +0000";
  DestinationID = "37599A9D-058E-4930-B6CF-B8D36A22D7FB";
  DestinationMountPoint = "/Volumes/Time Machine Backups";
  Progress =   {
    Percent = "0.0140759946587664";
    TimeRemaining = 3676840;
    "_raw_Percent" = "0.0140759946587664";
    "_raw_totalBytes" = 368132820992;
    bytes = 5181835622;
    files = 263033;
    totalBytes = 368132820992;
    totalFiles = 1173013;
  };
  Running = 1;
  Stopping = 0;
}


EDITED TO ADD:

Actually I just spotted cause for optimism; I ran 'tmutil latestbackup' and for the first time it doesn't reference my last backup in April, but has a timestamp of yesterday. Qualified success!

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Why is this Time Machine (Big Sur) failing -- here's the log

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