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macrumors 603
Original poster
Aug 6, 2015
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Earth
I have installed Catalina (10.15.1) on top of Mojave on Thursday. The installation itself went fine, but now my TimeMachine USB backup drive does not mount. The disc is connected, spins and flashes its lights as expected, but nothing appears in the finder, so I cannot actually backup at the moment. Any tips?
 

sugargliderdude

macrumors regular
Sep 27, 2019
148
308
I have installed Catalina (10.15.1) on top of Mojave on Thursday. The installation itself went fine, but now my TimeMachine USB backup drive does not mount. The disc is connected, spins and flashes its lights as expected, but nothing appears in the finder, so I cannot actually back up at the moment. Any tips?

You could try formatting a new USB and try backing up to that, see if that works...

I've seen other people moaning in MacRumors that time machine doesn't work with Catalina...

Maybe its because Catalina OS is now separated into its own partition????
 

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macrumors 603
Original poster
Aug 6, 2015
5,146
6,569
Earth
You could try formatting a new USB and try backing up to that, see if that works...

I've seen other people moaning in MacRumors that time machine doesn't work with Catalina...

Maybe its because Catalina OS is now separated into its own partition????

I will wait a bit to hear from those other Catalina pioneers before wiping the backup drive clean and starting again. From what I have read and see in my case, there are indeed two partitions in Catalina (Macintosh HD and Macintosh HD - Data), but I suppose Apple designed it this way on purpose? Will wait for more feedback for now...
 

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macrumors 603
Original poster
Aug 6, 2015
5,146
6,569
Earth
Ok, so I ended up erasing the Mojave backup drive with DiskUtility and now it is happily going through the backup. There is obviously something bizarre between Mojave and Catalina TimeMachines hand-over, but I did not feel like spending more time on it. FWIW, in the DiskUtility both Macintosh HD and Macintosh HD - Data partitions are marked as APFS (Encrypted), while the external backup drive - as Mac OS Extended (Journaled). The file systems were assigned to the disks by default during the Catalina installation and then selecting a new backup disk, so go figure...
 
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