INCOMPATIBLE DISK error message upon launching Big Sur APFS vs MacOS Extended issue in Big Sur?

Running on:
iMac 27" 5k late 2015 - 64gb ram and a 16tb Pegasus Promise2 R4 raid5 via Thunderbolt.
After trying Big Sur - found issues with Luminar Photo app, decided to return to Catalina on the iMac.
Reformatted my internal drive and reinstalled Catalina 15.5 and reformatted the raid. But I keep getting the following message upon restarting:

"Incompatible Disk. This disk uses features that are not supported on this version of MacOS" and my Pegasus2 R4 portion no longer appears on the desktop or in Disk Utility...

Looked into this and discovered that it may be an issue of Mac OS Extended vs APFS
The iMac was formatted to APFS prior to installing OS11 so I reformatted to APFS when returning to Catalina. The issues persisted so I re-reformatted from a bootable USB - this time to Mac OS Extended (journaled) and the issues seems to be resolved.
The iMac runs slower on MacOS Ext, but it is running and the Raid is recognised...
I'd love to go back to APFS but am afraid it will "break" things.

Any thought on this would be welcome.

Thanks

Nick

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NDTinBerlin
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I had the same problem. I only deleted the volume from the disk (Macintosh HD), not the entire disk (APPLE SSD) and the same error appeared after I reinstalled macOS Catalina (before I had macOS Big Sur).
I tried to erase the entire disk (APPLE SSD), APFS format and GUID partitioning. I then reinstalled macOS Catalina and the error did not appear.
I used the steps from Apple in the link to delete the entire disk.
https://support.apple.com/en-us/HT208496#erasevolume - "How to erase your disk"
Posted by
silviusescu
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I installed Beta Big Sur yesterday (10 Aug.) over beta Catalina on an external SSD. A hefty 12gb download, I might add! All went well. I was able to boot Into Big Sur from the external drive. BUT, when i booted into Mojave on my 2014 iMac, a warning came up that the external drive partition was not fully compatible with Mojave. I clicked continue and Mojave mounted a partition that contained none of my data but had the same capacity of the Big Sur installation. I chalked it up to a new ‘flavor’ of APFS which is not visible to previous systems to Big Sur. Can someone clear this up for me?
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geoMac
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the same with me. using macbook 12" early 2015, was testing the bigsur, but i do not like what it make my computer laggy.

going back to mojave, and all good now.

but it keep telling me the same alert everytime it rebooted.

how to fix this?
Posted by
rezashamdani
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The new format creates a container and at least one volume. You should erase both. After formatting (erase button in Disk Utility) in HFS, and after in APFS. The error message will disappear.
Posted by
ferasouder
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  • Thank you! I've been all over looking for this. You nailed it, so simple too.

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    datahjunky
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After erasing disk as suggested in multiple threats, I was still having the error message come up. Implementing this https://support.apple.com/en-au/HT208050 through Terminal - helped.

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Mykolavh
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  • Mykolavh, you posted the link to how setup ZSH as the main shell. Perhaps you meant to post something else?

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    prizrak
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This sounds good, but how do you go about getting rid of the incompatible disk message without repartitioning and erasing the whole disk?

On my Macbook Pro 2015, I had installed Ventura through a hack called Opencore Patcher, but after an update to 13.*.6, the graphics drivers were broken, so after reinstalling Opencore Patcher itself, it completely broke the system. So I booted using usb, copied my files and reinstalled Mojave (which flies twice faster as Ventura on the same machine so I will not upgrade again), but I had forgotten to repartition the hard disk.

I could get rid of Opencore's reliquate bootloaders by deleting its EFI's after mounting them manually from Terminal, but now I would like to get rid of this Incompatible message without reinstalling the whole system. I already spent some time reinstalling all my apps, accounts (Google's and Apple's are ... not to be taken lightly) and all my Macports so I would like to avoid the hassle and find a way to this from Terminal in Mojave.

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prizrak
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