Catalina installation error

Great question, now you have a few tools to help you, but it is somewhat a technical verification; but easy enough for most if you go slowly!

First, this specific error (during MacOS install) is most usually in relation to the "quality" of you MacOS partition. Simply, your Mac paritition has errors and sometimes it may be recoverable... Let's check this now.

1 - Boot your Mac in Recovery Mode (hold together on your keyboard -> command + R).

2 - Once loaded -> give it a moment or so, go into Disk Utility app -> you should see a menu with 4 options including reinstall your OS, get help, etc.

3 - Once in the App, you will see the drives you have on your Mac. Make sure you select the drive that holds your main paritition (usually on the top left menu). That's usually where you want to install you OS. Now in the sidebar, select the volume you wish to repair.

4 - Click the First Aid button -> Click Repair Disk.

Now if nothing seems to work (and you still get errors), you may have to recovery a broken partition using Internet Recovery or a Time Machine backup. Now that's another subject!

Respect.

Here's a great web site for futur reference : https://www.idownloadblog.com/2016/02/26/how-to-use-disk-utility-in-mac-recovery-mode/

How to fix a split Fusion Drive

If your Fusion Drive appears as two drives instead of one in the Finder, it's no longer working as a Fusion Drive. Here's how to fix it.

https://support.apple.com/en-gb/HT207584

If you're using macOS Mojave or later

1. Turn on your Mac, then immediately press and hold Command-R to start up from macOS Recovery. Release the keys when you see the Apple logo or spinning globe.
2. When you see the macOS Utilities window, choose Utilities > Terminal from the menu bar.
3. Type  diskutil resetFusion in the Terminal window, then press Return.
4. Type Yes (with a capital Y) when prompted, then press Return.
5. When Terminal indicates that the operation was successful, quit Terminal to return to the macOS Utilities window.
6. Choose Reinstall macOS, then follow the onscreen instructions to reinstall the Mac operating system. Your Mac restarts from your Fusion Drive when done.

I wonder if you have checked the ‘all devices’ item in the drop down at the top left of disk utility. When I tried to repair ‘container disk 2x’ which contained my Macintosh HD partition, I found it failed verification. As it turns out, there are a number of partitions that are not mounted which appear to have been created by the j stall routine (since Catalina creates two separate partitions, one for the Os files and one for data.

anyway, long story short... needed to recreate the fusion drive from the recovery terminal (after Backup, of course). After recreation, installation worked fine. Just restoring from tome machine now....

This is crucial and bad UX design by Apple.

All devices must be displayed so that the container can be selected and erased (formatted). Only by erasing the container will Disk Utility setup the extra volumes needed by Catalina. If you just erase the Macintosh HD volume (which by default is all that is shown) then only that volume is erased which means the Catalina install will fail because it cannot find the other volumes it needs (system and boot I believe).

Many thanks JA-A.

OK. Tried all the suggestions and none worked. Bit the bullet, backed up everything, booted from a flash drive and erased the Macintosh HD. Then reinstalled Mojave, ran Disk Utility and then installed Catalina. Seems stable now except it created two versions of Macintosh HD - data. I had to rename one so Time Machine would work again.

I used internet recovery ... I found out what the problem was, and I found a solution. There seemed to be a partition on my drive, that I couldn't delete nor change. Maybe I was hacked? Anyway, first, I erased the Fusion Drive completely, deleting all APFS partitions and/or containers. Then I made one partition in HFS+, and then deleted the fusion drive again, and made a APFS container. Now Catalina is installed, and works fine.

Unfortunately I've had the same issue.

After trying the First Aid within the Disk Utility, it said there was still an issue on the HD (I too have a fusion). I eventually pulled all the files from my computer and did a clean install. It went back to Mojave 10.14. and while still being clean of third party apps or whatever I updated to Catalina. No more error.

It takes a little longer than you're used to, but it seems to work fine now. It might be the unconventional way to work because of the files and stuff. But it's also a great reason to clean up your computer ;)..

HugoRod1024:

Suggestion #1 was a waste of half an hour. I did the Option + Command + P + R three times and then tried the Catalina install again. Same error as before.

This is definitely a Fusion hardware issue. I think that the drive is bad and needs to be replaced, so I'm taking my machine in next week.

Reformatting the Fusion drive and then restoring from Time Machine may get the job done, but there has to be a reason as to why the Fusion drive is getting messed up.

Hi HerrDV. Looks right to me.

I see that Patmore responded to your posting and suggested using the Catalina Disk Utility to remove the partitions. Please note, I have not tried this, but it should work the same way as I suggested (but without the terminal :)

Make sure you have taken many backups to ensure you have everything you need to restore and make sure you have a "bootable" USB stick with Catalina on there and you are ready to go.

I should want you that my restore from backup took 7 hours, so you will also need patience (and a large supply of coffee ;)

JAA

Same error here! iMac Retina 5K 27-inch, Late 2015.

Ran Disk First Aid and received an error and tried to repair – no luck. Started up in Recovery mode and ran Disk Utility again with same result. The Fusion drive seems to have issues with no immediate user-friendly way to repair it.

1steffano:

Thank you, this is valuable input. It does seem that erasing the Macintosh HD is the solution. But we all need to know from Apple what is causing the Fusion drive in becoming messed up?

I had this problem months ago when I could not update from High Sierra to Mojave. I took my machine in and the Authorized Apple Service Center said I had bad 3rd party RAM. They removed the supposed bad RAM, reformatted the Fusion drive, installed Mojave and then I had to restore everything from Time Machine.

So here I am again, unable to update to Catalina because the Fusion drive is yet again messed up. I'm taking my iMac in next week to see what the excuse will be this time.

Going forward, this is just not right, and Apple is saying nothing to address the Fusion drive corruption issue. Do we all have defective Fusion drives? Nobody is saying...

Unfortunately for my case, this did not help :( Both times the repair is successful (even in Recovery Mode) but I still get the error when installing Catalina. I get no errors during the disk repairs... very odd :(

I'm having exactly the same problem with the same model iMac. Mine has 3 TB fusion boot drive formatted to AFS. It is passing all the test in the disk utility program.

I have booted to recovery, run the re-install of Mojave, tried booting to USB but I cannot get an upgrade to run.

I'm reluctant to format the drive and do a new installation, It has taken my long enough to get the machine as I want it to start again!

What's crazy is that I attempted this. I formatted the harddrive, installed a fresh new Mojave and when I attempted the update I got the SAME error. Very frustrating since it took a long while. I hope a solution can be found soon.

Same issue. Did the Disk Utility which reported no errors. Booted into Safe Mode, downloaded fresh installer - still got the same issue.

Really don't want to have to clean my Mac and start again but it's looking like I might have to... hopefully Apple comes up with an answer first!

iMac 5K Late 2014