I am having a similar issue - here is the description why it happened to me. I called the Apple support and they explained to me, that my issue is probably not solveable so may the following be a warning for you, dear reader, what you should NOT do: Migrate your old MacBook Pro to a new MacBook Pro with T2 chip using Carbon Copy Cloner, instead of Apple's built-in migration assistant.
Jan 21, 2017 Download Carbon Copy Cloner from the developer’s website. Locate and unpack the downloaded ZIP file in your Downloads folder. Using your cloning software of choice, clone your physical Mac/hard disk/clone/disk image file of your old system to the additional virtual machine drive e.g. With Carbon Copy Cloner: In the virtual machine go to Apple menu System Preferences Startup Disk set it to 'Second HD'. Downloading and installing Carbon Copy Cloner version 5 on macOS High Sierra.
Carbon Copy Cloner Windows Alternative
Here is what I did that lead to the catastrophy:
- Unpacked my brand new MacBook Pro and booted it once to have a 'temporary admin'.
- Used the Startup Security Utility (used the password of this temporary admin) to allow booting from an external HD
- Upgraded my old MacBook Pro to Mojave and used Carbon Copy Cloner to make a clone of the HD
- Booted the cloned HD on my New MacBook Pro (which worked like a charm because I allowed this inside Startup Security Utility)
- Used Carbon Copy Cloner (CCC) to clone the external boot HD to the internal MacBook's HD
- Removed the external HD
- Rebooted my new MacBook
- WORKED LIKE A CHARM: The new MacBook 'feels' like the old one, my old admin user is there, all my apps are there, I can configure everything. Everything just works.
- Well - not everything: When I tried to go back to the Startup Security Utility with the intension to now disable the right to boot from external HDs (to increase security, because I only wanted to allow this for my migration via CCC) the error message 'No administrator was found.' is coming up.
All my attempts to resolve this, e.g. by deleting PRAM or SMC or creating a new admin, then reboot and then try this one: All failed.
Now, I am sitting here with a brand new MacBook Pro and a seemingly unresolvable gaping security hole.
I cannot really believe that this is really an unresolvable issue, so I will try more Apple support employees by calling the support again and I will try to google even more. If I'll resolve it, I'll post the solution here.
If somebody solved it - would be glad to learn from you.
Oct 5, 2018 6:55 AM
Apple took system protection to the next level in macOS 10.15 Catalina by splitting your normal boot volume into two pieces. It appears like a single volume on the Desktop, but it’s really two: one is labeled with the volume’s name, while the other has “- Data” appended to it.
The new main volume is read only and contains only operating system files. This doubles down on the previously added System Integrity Protection (SIP) feature, which prevented key files from being modified as a way of reducing the potential for malware exploitation. This new approach in Catalina is a more severe version of this.
The Data volume contains everything else, and is tagged in Disk Utility with a Home icon over its disk icon in the descriptive view. By using new APFS features in Catalina, Apple can create a “volume group” that links the system and Data volumes together as a single item in function, and use “firmlinks” that allow cross-volume symbolic links without duplicating files, further tying the two logically distinct items together. Bombich Software, makers of Carbon Copy Cloner, has a more detailed explanation on their blog. (And note that if you mount a Catalina drive in Mojave, both volumes mount correctly, but appear separately and unlinked.)
During the upgrade from a previous macOS to Catalina, Apple moves any files that are located in a path that can no longer be written by the user to the Home directory’s Shared folder in “Relocated Items.”
When you start up Catalina, you don’t see two volumes on the desktop—just one, and it’s named as you would expect, with the plain name of your volume as you set it. Apple manages that trick by hiding the “- Data” volume, even though it’s mounted, and using firmlinks to make sure all the files in the Home directory and other read/write areas of macOS are mapped to the correct place.
This only gets confusing when things go awry. I’ve heard from several readers and read in a number of forums that the Data volume sometimes appears on the Desktop as another accessible volume. One reader even found that Time Machine refused to run after they had updated to Catalina because it found two copies of the “iMac – Data” volume, possibly because the reader had a backup mounted.
I don’t yet have an explanation as to why this happens, although it may have to do with the significant updates required for disk cloning software to work correctly with volume groups, firmlinks, and Catalina. If you clone or copy your Catalina startup volume with a utility not yet ready for Catalina or while booted into Mojave, it’s likely you create two disconnected volumes instead of a unified Catalina whole. (Carbon Copy Cloner is ready for Catalina; Shirt Pocket’s SuperDuper! update is in its final beta testing stage.)
Time Machine can backup a Catalina startup volume group to a HFS+ drive, although you should only attempt to interact with such a backup within Catalina—in Mojave, Time Machine won’t know precisely how to deal with it.
This Mac 911 article is in response to a question submitted by Macworld reader Bill.
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Carbon Copy Cloner 10.6.8
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