MacOS – Consistent TM errors (-36 and -8062) when trying to backup to an external drive

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Since moving to a new MBP I am having endless of trouble with TM backups. They practically all fail, at different time points, with different files being the culprits (see below).

I have a WD MyBook Duo, which is an external drive chassi with two bays and some software that allows for running RAID (which was the entire reason for me to buy this device). I have tried to repair, erase and reformat the drive(s) it doesn't help. I have reset the Time Machine prefs and started from scratch, no avail. I have also tried connecting the disk to different USB-C ports (always via an Apple adapter) and even tried to remove all the other cables on the adapter. Still no joy… 

2017-06-14 16:36:31.725929+0200 0xbf16c    Error       0x0                  12956  backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Error: (-36) SrcErr:NO Copying /Applications/Adobe Acrobat X Pro/Adobe Acrobat Pro.app/Contents/Frameworks/AdobeAGM.framework/Versions/A/AdobeAGM to /Volumes/Backup1/Backups.backupdb/my mbp/2017-06-14-163502.inProgress/FA66CBD8-0F8E-4952-A4FC-D29F5A501C45/Macintosh HD/Applications/Adobe Acrobat X Pro/Adobe Acrobat Pro.app/Contents/Frameworks/AdobeAGM.framework/Versions/A
2017-06-14 16:36:31.726334+0200 0xbf16c    Error       0x0                  12956  backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Stopping backup.
2017-06-14 16:36:31.726464+0200 0xbf16c    Error       0x0                  12956  backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Error: (-8062) SrcErr:NO Copying /Applications/Adobe Acrobat X Pro/Adobe Acrobat Pro.app/Contents/Frameworks/AdobeAGM.framework/Versions/A/AdobeAGM to /Volumes/Backup1/Backups.backupdb/my mbp/2017-06-14-163502.inProgress/FA66CBD8-0F8E-4952-A4FC-D29F5A501C45/Macintosh HD/Applications/Adobe Acrobat X Pro/Adobe Acrobat Pro.app/Contents/Frameworks/AdobeAGM.framework/Versions/A
2017-06-14 16:36:31.729806+0200 0xbe7af    Info        0x8000000000033a6a   12956  backupd: (TimeMachine) [com.apple.TimeMachine.TMLogInfo] Copied 3606 items (679,2 MB) from volume Macintosh HD. Linked 0.
2017-06-14 16:36:31.730372+0200 0xbe7af    Error       0x8000000000033a6a   12956  backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Copy stage failed with error:11
2017-06-14 16:36:31.740639+0200 0xbe7af    Error       0x8000000000033a6a   12956  backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Backup failed with error 11: 11

The actual files change, probably since the backup failures happen at different time points. As an example here's another chunk out of the logs

2017-06-14 13:34:05.894647+0200 0x2e1612   Error       0x0                  5233   backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Error: (-36) SrcErr:NO Copying /Applications/iMovie.app/Contents/PlugIns/MediaProviders/MotionEffect.fxp/Contents/Resources/Templates.localized/Transitions.localized/Stylized.localized/Sports.localized/Swoosh.localized/Media/BKG.mov to /Volumes/My Book Duo-2/Backups.backupdb/my mbp/2017-06-14-131746.inProgress/0CBC2EF4-85AD-41B2-8E8E-945E06A49E46/Macintosh HD/Applications/iMovie.app/Contents/PlugIns/MediaProviders/MotionEffect.fxp/Contents/Resources/Templates.localized/Transitions.localized/Stylized.localized/Sports.localized/Swoosh.localized/Media
2017-06-14 13:34:05.901974+0200 0x2e1612   Error       0x0                  5233   backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Stopping backup.
2017-06-14 13:34:05.902047+0200 0x2e1612   Error       0x0                  5233   backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Error: (-8062) SrcErr:NO Copying /Applications/iMovie.app/Contents/PlugIns/MediaProviders/MotionEffect.fxp/Contents/Resources/Templates.localized/Transitions.localized/Stylized.localized/Sports.localized/Swoosh.localized/Media/BKG.mov to /Volumes/My Book Duo-2/Backups.backupdb/my mbp/2017-06-14-131746.inProgress/0CBC2EF4-85AD-41B2-8E8E-945E06A49E46/Macintosh HD/Applications/iMovie.app/Contents/PlugIns/MediaProviders/MotionEffect.fxp/Contents/Resources/Templates.localized/Transitions.localized/Stylized.localized/Sports.localized/Swoosh.localized/Media
2017-06-14 13:34:06.001246+0200 0x2b7d1e   Info        0x8000000000017d9b   5233   backupd: (TimeMachine) [com.apple.TimeMachine.TMLogInfo] Copied 154575 items (7,06 GB) from volume Macintosh HD. Linked 0.
2017-06-14 13:34:06.001665+0200 0x2b7d1e   Error       0x8000000000017d9b   5233   backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Copy stage failed with error:11
2017-06-14 13:34:06.515762+0200 0x2b7d1e   Error       0x8000000000017d9b   5233   backupd: (TimeMachine) [com.apple.TimeMachine.TMLogError] Backup failed with error 11: 11

I have been all over WD homepage, but nothing useful there either. At this point my working hypothesis is that firmware on the disk cabinet is messed up or incompatible with USB-C somehow because:

  1. The same disk was working without any hiccups with my 2014 MBP.
  2. I can use another, stand alone external disk for backing up the new MBP.

but that doesn't really make a lot of sense either.

Any suggestions? What do these specific error codes mean, is there a listing for these perhaps?

Best Answer

I have had some success on this recently, sharing it here for future reference to others.

It is a long story but the bottomline is; get a USB hub with separate power line, connect the external disk to the hub.

It is likely that the power supply of the USB contact on Apple's multiport video adapters (USB-C, HDMI, USB-A) is likely to be unstable. If the USB controller on the external disk takes its power from the USB contact rather than the power supply of the disk (apparently not an uncommon solution), then TM backups fail stochastically bur reproducibly due to dropped connection which show up as I/O errors in the logs. A USB-hub with separate power supply resolves the situation.

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