Time Machine error with Catalina

I had this same problem. I installed the beta of Catalina back in June, but then decided against that and did a clean install. Then this month, I installed the release version of Catalina. So I also had two Catalina installs and two "Macintosh HD - Data" partitions. Here is how I solved the problem:

• Opened Disk Utility
• Found the partition that was only 1.6MB (the other was 185GB)
• Unmounted this partition
• Deleted this partition
• Rebooted
• Time machine works!

Please note: I am not an expert in APFS and it's entirely possible deleting that partition is going to cause me problems down the road. So if you do this make sure you're comfortable deleting a partition. Cheers!

Can you type the following into a Terminal window (Terminal.app is located in /Applications/Utilities) and post results:

df -kt
diskutil list
tmutil latestbackup

change any personal info but do it in the same way so we can see what is really the same and what is really different.

Good luck...

I have the same issue. I did a clean install of Catalina .

Filesystem    1024-blocks       Used  Available Capacity  iused      ifree %iused  Mounted on

/dev/disk3s6    536768492   10299272  342008140     3%   481695 5367203225    0%   /

devfs                 203        203          0   100%      705          0  100%   /dev

/dev/disk3s5    536768492  181358680  342008140    35%   181452 5367503468    0%   /System/Volumes/Data

/dev/disk3s4    536768492    2098196  342008140     1%        2 5367684918    0%   /private/var/vm

map auto_home           0          0          0   100%        0          0  100%   /System/Volumes/Data/home

/dev/disk0s3    439322776  361185244   78137532    83%   714139   78202401    1%   /Volumes/BOOTCAMP

/dev/disk3s1    536768492     245020  342008140     1%   129479 5367555441    0%   /Volumes/Macintosh HD - Data

/dev/disk2s2    468515632     437276  468078356     1%      178 4294967101    0%   /Volumes/MAC DATA 3

/dev/disk1s2    116884912     217536  116667376     1%       99 4294967180    0%   /Volumes/MAC DATA 5

/dev/disk4s2   3906682672 3700189128  206493544    95% 11920367 4283046912    0%   /Volumes/MAC DATA 2

/dev/disk5s2   5859031000 2628623056 3230407944    45%   476864 4294490415    0%   /Volumes/MAC DATA

/dev/disk0 (internal, physical):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *1.0 TB     disk0

   1:                        EFI EFI                     209.7 MB   disk0s1

   2:                 Apple_APFS Container disk3         549.7 GB   disk0s2

   3:       Microsoft Basic Data BOOTCAMP                449.9 GB   disk0s3

   4:           Windows Recovery                         827.3 MB   disk0s4

/dev/disk1 (external, physical):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *120.0 GB   disk1

   1:                        EFI EFI                     209.7 MB   disk1s1

   2:                  Apple_HFS MAC DATA 5              119.7 GB   disk1s2

/dev/disk2 (external, physical):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *480.1 GB   disk2

   1:                        EFI EFI                     209.7 MB   disk2s1

   2:                  Apple_HFS MAC DATA 3              479.8 GB   disk2s2

/dev/disk3 (synthesized):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      APFS Container Scheme -                      +549.7 GB   disk3

                                 Physical Store disk0s2

   1:                APFS Volume Macintosh HD - Data     250.9 MB   disk3s1

   2:                APFS Volume Preboot                 82.3 MB    disk3s2

   3:                APFS Volume Recovery                528.9 MB   disk3s3

   4:                APFS Volume VM                      2.1 GB     disk3s4

   5:                APFS Volume Macintosh HD - Data     185.7 GB   disk3s5

   6:                APFS Volume Macintosh HD            10.5 GB    disk3s6

This is very confusing -- it appears that you do have two logical volumes named "Macintosh HD - Data" - one is only 250.9MB (named disk3s1 and one is 185.7GB named disk3s5 on the 550GB APFS container that is physically on the 1TB internal drive -- perhaps you had to try two different times to install Catalina? Sorry, but i've no idea how to untangle your situation, but if I figure something out will post later. Sorry...perhaps someone with APFS expertise can give advice on how this might have happened and how to untangle it.

However the output you posted didn't show the commands you used -- that would help to see the command you typed and the output it produced, plus the list of drives seems incomplete as there is no disk4 or disk5 device shown on the "diskutil list" command but they are listed on the "df" command so it's very confusing to see inconsistent info like this.

Good luck...

Yes, I installed Catalina twice. First, I upgraded from High sierra to Catarina, and next I did a clean installation of Catarina.

I remembered "Macintosh HD - Data" already existed when I used disk utility before I did a clean installation but I didn't delete it.

And now I saw two "Macintosh HD - Data" volumes .

I decided I did a clean installation again this morning.

First of all, I deleted two "Macintosh HD - Data" volume before I installed Catalina . And now I successfully installed Catalina and Time machine is working correctly without error.

Thank you very much .

I have a similar problem: Here are my disk outputs...

Disk3 below is my external Time Machine Drive.

]% df -kt
Filesystem    1024-blocks       Used Available Capacity  iused      ifree %iused  Mounted on
/dev/disk1s5    976797816   10839840 250313420     5%   481895 9767496265    0%   /
devfs                 201        201         0   100%      698          0  100%   /dev
/dev/disk1s1    976797816  711699596 250313420    74%  4121814 9763856346    0%   /System/Volumes/Data
/dev/disk1s4    976797816    3146812 250313420     2%        4 9767978156    0%   /private/var/vm
map auto_home           0          0         0   100%        0          0  100%   /System/Volumes/Data/home
/dev/disk2s2   4883303600 3909763256 973540344    81% 37437533 4257529746    1%   /Volumes/Time Machine
/dev/disk3s2   4883303600 3907452296 975851304    81% 37436668 4257530611    1%   /Volumes/Time Machine 1



% diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         1.0 TB     disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1.0 TB     disk1
                                 Physical Store disk0s2
   1:                APFS Volume Mandrenke HD - Data     728.8 GB   disk1s1
   2:                APFS Volume Preboot                 80.5 MB    disk1s2
   3:                APFS Volume Recovery                528.9 MB   disk1s3
   4:                APFS Volume VM                      3.2 GB     disk1s4
   5:                APFS Volume Mandrenke HD            11.1 GB    disk1s5

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *5.0 TB     disk3
   1:                        EFI EFI                     209.7 MB   disk3s1
   2:                  Apple_HFS Time Machine            5.0 TB     disk3s2

% tmutil latestbackup
/Volumes/Time Machine 1/Backups.backupdb/mandrenke/2019-10-11-141213

You should post another question rather than piggy back onto this one -- your situation is different than OP. Don't want to confuse other people when I make a suggestion to solve your problem as it's not at all gonna address the problem with having two "Machintosh HD - Data" partitions. There are already two threads running in this discussion that don't have anything to do with each other, don't want to make it three.

But I will make one suggestion for you -- reboot your system in safe mode and then again in normal mode. And post back a new question if it's still a problem.

Good luck...

Just has this problem, and took the rash decision to delete and erase the smaller duplicate. Time will tell if it worked: if the worst comes to the worst, I'll reboot and resinstall from my CC+ clone and try again.

Brian

As I appeared to have two instances of "Macintosh HD [Data]", and had recently made a complete bootable clone of my mac with Carbon Copy Cloner (and tested it!), opened Disk Utility and zapped the smaller of the two mirrored drives.

Everything seems to be working perfectly, and Time Machine is functioning once more.

Brian

I have a similar issue as Yassie2: New computer started with time machine backup of HighSierra (new computer had Mojave) - upgrade to Catalina. Issues with drivers.

Then clean install of Catalina - 2 Mackintosh-Data volumes: 1) @ Volumes/ Mackintosh HD - Data - 322 GB used modified today 16:14 pm, Name & Extension: Mackintosh HD - Data; 2) @ System - Volumes Data - Mackintosh: Name & Extension: Data; Data 310 GB used modified today 13:10 pm

So my bet would be the 2nd volume is not necessary and I will rename it and monitor, whether it changes (will be modified), before I delete it. At the moment it is eating storage space.

Would be nice to see an Apple response here. Need to find out where I can file a bug report.

This from another Forum...

Well I re-'upgraded' to Catalina yesterday and immediately TM broke. Somehow there were two Macintosh HD - Data volumes and it didn't know which to use. Similarly, I didn't know why it happened or what to do. I did search and it seems I am not alone with this glitch. As it was getting late, I left it overnight.

Today I had a chat with Apple Support and after explaining, sending screenshots and more information than they asked for, they admitted defeat and had me passed to a Software Engineer who rang me back. We had a remote screen session, he identified which was the surplus Data volume and he advised how to delete it, after securing data that was duplicated, just in case there was an issue. That is done and TM now says it is preparing the backup. It is taking time to get round to the actual backup. I was asked to re-schedule a call from Apple to confirm it is sorted. I'll do that when TM has completed.

https://www.mac4mac.co.uk/viewtopic.php?f=2&t=6869&sid=cf3a52c813619438b875ec1dd11fe792&start=30

If it happens to you, the volume you want to keep has the House icon overlaid on the HD icon (in Disk Utility).

Thank you BDAquq, just the last confirmation I needed! I saw that one of the Macintosh HD - Data disks had the House icon and I also tested that that was the one, where newly created user files go. It is the ‘hidden’ volume in Macintosh HD - Systems.

I found also that I had to do something - not only because of the impact on Time Machine: as the system is confused, some of the newly installed applications landed in the additional, wrong partition! And then of course, don’t show up in Finder Applications, even though functional. And the iCloud Drive backup (when I turned it off) also ended up in the wrong partition.

So I moved the data that were created there since upgrade to my Desktop. Apart from the Applications, as that will not work. Then I unmounted (and therefore erased) the additional volume without the House icon for the user folder with the Disk Utility. Installed all lost applications again and all is working fine as far as I can tell, including Time Machine and all Applications, showing up in Finder.

I too have suffered from this problem. But, I am pleased to report that installing the MacOS Catalina 10.15.1update fixes the problem. I was hoping it would, but I wasn't sure because the support notes for the update don't explicitly mention the problem. Cynically, it would appear Apple is too image-concious to report the bug in the support notes, even if the report gives a positive outcome: "it's fixed".

Yes, I took the advice shown in the above alert and renamed one of the DATA volumes. I believe having multiple volumes was a consequence of having installed 10.15.1 and restoring my files and then re-installing again because I ran into a number of extremely odd problems (like not being able to empty the trash using every trick in the book!). I chose to not wipe the disk clean but rather just install the OS and I think this may have been a mistake. I also ended up with 2 APFS groups called "DATA" which time machine did not like.

Changing the name of one of the disks (with Disk Utility) seemed to appease time machine but I feel a bit uneasy. Hopefully I will be able to restore correctly from the backup. I intend to check this out as soon as the backup completes.

Launch Disk Utility and you will see the 2 standard APFS volumes: "Macintosh HD" and "Macintosh HD - Data." I, like some others who did multiple Catalina reinstalls found 2 "Macintosh HD - Data" volumes which caused the TM complaint. Right click (or control-click) on one of the "Data" volumes and you will see an option to "Rename." I am not sure if it matters but I did not rename the Data volume that was badged with a "Home" icon.

Time machine backed up but when I tried to do a restore I did not see the files on the renamed Data partition. I decided to remove the renamed partition using Disk Utility. Then TM seemed to function correctly both backing up and restoring.