When I started my day I noticed that my Desktop Time Machine icon was missing. The TM preferences panel indicated that it had been "disconnected", and it hadn't backed up anything for ca 8 hours.

Checking the Console log I was informed that the standard backup had failed due to
"Error -35 while resolving alias to backup target" and subsequently
"Backup failed with error: 19".
I have no idea what those errors are or might indicate ... and would like to know.

I ran Disk Utility (Repair Disk) on the backup hard drive (Western Digital My Passport 0740 1TB USB Drive) which found the media to be OK but when I ran Repair Disk on the volume it supposedly "stalled out" with over an hour left to run. When I cancelled the repair, it seemed to be happy and even ran a backup (ostensibly) successfully.

Nothing else seems to be awry with the iMac (2.5GHz Intel Corei5 / 4GB 1333MHz DDR3) running Mac OS X Lion (10.7.5).

Any explanatory commentary out there?

sounds like a failed hard drive

imho, time machine drives should be replaced every 1-2 years. If the old one still works, keep it. slap a label on it and stick it somewhere safe as an archival backup. Get a new drive and use that for the next year or two.

Could be, but it's been happily and successfully backing up on its own and when asked to since my previous post.

nevertheless, my advice to periodically replace them still stands.

No argument; I agree.

Still, I'd like to know what those error messages (-35, 19) are. Is there a "glossary" somewhere which might explain them?

" . . . Still, I'd like to know what those error messages (-35, 19) are. Is there a "glossary" somewhere which might explain them? . . . "

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I get those messages from time to time, too. I do NOT have my Time Machine on auto backup. I manually hit "click" when I wish to do a backup with TM on Apple's Time Capsule with Wi-Fi.

The TM will hang in "preparing mode" and then the error message will appear. I click "backup now" again and it rights itself. Backup begins.

On a side note: Even with minimal changes since the last backup, some new backups seem to hit 1.5 GB. It appears that something keeps backing up which does not really need to be (???)

I haven't been too concerned since I have only used 180 of the 1000 GB available on the TC. Still, I do wonder why the 1.5 GB backup happens at times when (I think) there have been very few additions, deletions or other changes to the files and folders which are being backed up.

P.S. I did a System (folder) backup for the FIRST time only. Time Machine preferences are set to ignore this folder on subsequent backups.

According to the list of error codes found in MacPilot 8…

Thanks. Not overly enlightening however. Oh well ...

Error codes are seldom very enlightening. A search of the log files for backupd entries might provide more information.

If I had to interpret just from the two error codes I would suspect at that point in time TM had attempted to open the TM drive and for whatever reason it could not be contacted. That could imply...

• The drive had for one reason or another been dismounted (I have one that inexplicably does that once in a while — I don't use it except for experimental work — which may be why it disconnects) 😒
• drive response was slow and the contact attempt timed out 🙄
• If the TM volume is used by more than one Mac it was busy when your system attempted to contact it 👾
• if it is a network attached drive, network traffic might have prevented the connection. 😳
• an internal system error 😱
• nothing to worry about unless it recurs 🤔
• recurs at an increasing frequency 😭