Suddenly, Time Machine won't backup

[Henri9009]

Hi all!

This is really strange. I just bought a new (used) iMac. I restored my hard drive content on the new computer, with a Time Machine backup, and it went all fine. High Sierra OS.

Now that I'm on my new iMac, Time Machine won't make backups. I'm mentioning that it doesn't seem to be a hard drive problem, because I have two Time Machine backup hard drives, and it doesn't work with neither of them.

As a hard drive problem was my only lead, I tried everything I found on the Web (repair and others). Nothing worked. The last solution: format the drive. It still doesn't work.

I'm clueless here. Any ideas?

Thanks a lot!

 

[Fishrrman]

Try either CarbonCopyCloner or SuperDuper.
They... just work.

 

[Brian33]

That is strange. I haven't seen that error before.

You say you formatted the backup drive. Does the error message always have the correct volume name? Just to be clear, did you go to System Preferences-->Time Machine-->Select Disk and remove the old setting, then select the newly-formatted drive? I guess you did, but just checking...

Are you comfortable with Terminal commands, and wading through a bunch of log messages? See my post about the 'log' command in https://forums.macrumors.com/threads/time-machine-showing-not-backed-up.2272440/

 

[Henri9009]

Brian, for your first paragraph, the answer is yes.

I'm comfortable with commands... here are the two main messages:

Backup failed because a backup source disk was ejected or disconnected unexpectedly!

The backup disk could not be found.

By the way, I'm having that ejecting problem (also a new problem, never had that problem with my old computer, although all with the same gear), external hard drives, docking station, after a come back from sleep mode.

Thank you!

 

[Brian33]

Backup failed because a backup source disk was ejected or disconnected unexpectedly!

The backup disk could not be found.

Yikes! Wish I had some great suggestion about the ejecting problem, but all I can think of is changing "Put hard disks to sleep when possible" in System Prefs-->Energy Saver (or whatever it is in High Sierra).

 

[Henri9009]

"Put hard disks to sleep when possible" must be unchecked, right? That's what I found on the Web. That's the way it was when I posted that message.

Thanks anyway Brian!

 

[Henri9009]

Finally, it works now, after I did these two things (update to Mojave and delete the "data HD" that was left as a result of a previous Catalina install). I think that it is the deletion of the "data HD" that did the thing, because right after the Mojave install restart, I tried Time Machine and it was not working.

Actually, the guy sold it to me with Catalina installed, but as I didn't want to have to cope with application incompatibilities, I went into Recovery Mode, erased the Macintosh HD and installed my last Time Machine backup (on the HD that was not named "data").

 

[Quackers]

Finally, it works now, after I did these two things (update to Mojave and delete the "data HD" that was left as a result of a previous Catalina install). I think that it is the deletion of the "data HD" that did the thing, because right after the Mojave install restart, I tried Time Machine and it was not working.

Actually, the guy sold it to me with Catalina installed, but as I didn't want to have to cope with application incompatibilities, I went into Recovery Mode, erased the Macintosh HD and installed my last Time Machine backup (on the HD that was not named "data").

I think TM refuses to back up a drive that has two volumes with the same name - ie Macintosh HD - Data

 

[Brian33]

Good job getting it sorted out!

Backup failed because a backup source disk was ejected or disconnected unexpectedly!

I think that it is the deletion of the "data HD" that did the thing,

I think TM refuses to back up a drive that has two volumes with the same name - ie Macintosh HD - Data

I'd made a big mistake and mis-read the "Backup failed" message -- I hadn't realized that it specified the source disk as the problem, and had assumed that it was talking about the external destination disk! I think Quakers may be right about the cause; too bad TM didn't give better error messages.

Catalina (and Big Sur) with their multiple APFS volumes have really caused a lot of trouble for people that go back to Mojave or High Sierra. Glad you got it working.