Time Machine keeps failing to back up

[bivalvegruff]

I've tried three different external hard drives – the back up initiates, goes to maybe 50 %, then says it couldn't complete it. No more information. All hard drives are erased and formated as Mac OS Extended, journaled, encrypted. What could be wrong?

 

[CoastalOR]

There could be some file corruption on the drive you are trying to backup. TM just gives up when encountering a problem file. You could try a demo of Carbon Copy Cloner (CCC) to do a backup to 1 of your 3 drives. It is fully functional for 30 days in demo mode. CCC will continue to copy and skip problem files. CCC will provide a list of problem files it could not copy at the end of the clone.

 

[bivalvegruff]

You were absolutely right, @CoastalOR CCC found problems with files belonging to "App cleaner & uninstall". I deleted said app and its files, and now TM works again. Thank you!!

I'm gonna play around with CCC a bit, I do like the nativeness of TM but CCC definitely seems more heavy-duty.

 

[Brian33]

Glad you found out the problem files. If you ever need to in the future and don't mind using Terminal.app, there's a (somewhat cumbersome) way to show the log messages of the Time Machine process, which would likely point you to the specific files or other errors.

Open Terminal.app, enter the following "log" command, and then start a manual backup. You'll see a lot of messages scroll by. Hit Ctrl-C to end the command, or just quit Terminal and click on the "Terminate" button in the pop-up window.

log stream --style syslog --predicate 'senderImagePath contains[cd] "TimeMachine"' --info

If you replace the word "stream" with "show" it will show you log messages of previous backups.

 

[bivalvegruff]

Glad you found out the problem files. If you ever need to in the future and don't mind using Terminal.app, there's a (somewhat cumbersome) way to show the log messages of the Time Machine process, which would likely point you to the specific files or other errors.

Open Terminal.app, enter the following "log" command, and then start a manual backup. You'll see a lot of messages scroll by. Hit Ctrl-C to end the command, or just quit Terminal and click on the "Terminate" button in the pop-up window.

log stream --style syslog --predicate 'senderImagePath contains[cd] "TimeMachine"' --info

If you replace the word "stream" with "show" it will show you log messages of previous backups.

Awesome, thanks! How do you know these commands – they seem impossible to learn or remember, seems like you'd have to look it up each time?

 

[Brian33]

Heh heh, yeah the commands are sometimes pretty arcane, and the "log" command is one of the worst, I think. While I use a lot of Terminal commands, this one I copied from someone else's posting somewhere. You can learn all about it by using the "man" command, which displays the manual-page for any given command.

I.e., "man log" will show you the help page for the log command, and "man man" will show you how to use the man command. Have fun!
[doublepost=1551302965][/doublepost]Adding: when I think I will want to use a complicated command in the future, I'll put it in a bash shell script. E.g., I put these log commands into scripts called "tm-show" and "tm-stream", so that's all I have to remember for next time.