Help - Disk Issue Now?

[ColdShadow]

Isn't there any solution to this mess yet?
I'm also having the same problem,Big Sur was laggy and noticeably slow on my iMac Late 2015 with SSD,so I reinstalled Mojave using internet recovery + USB installer and now every time I boot I get this error message.

I tried modifying partitions in disk utility but it just gives me an error message in the end.
this is how my disk partitions look.

 

[Furka]

Ye, I have suffered the same problem when I retrofitted Mojave after a Big Sur upgrade. The problem is that Catalina/BS formats the HD in 2 units: System and Data, while Mojave formats in one big unit, not 2. In my case I have followed these steps :

1. Make a Backup of your Data/Apps etc
2. Reformat the Macintosh HD with a Mojave Disk Utility
3. Re-install Mojave and restore all from the Backup

I wish this helps

 

[ColdShadow]

Ye, I have suffered the same problem when I retrofitted Mojave after a Big Sur upgrade. The problem is that Catalina/BS formats the HD in 2 units: System and Data, while Mojave formats in one big unit, not 2. In my case I have followed these steps :

1. Make a Backup of your Data/Apps etc
2. Reformat the Macintosh HD with a Mojave Disk Utility
3. Re-install Mojave and restore all from the Backup

I wish this helps

When I attempt to repartition the disk from startup disk utility,it still creates multiple partitions and there is no way to merge them all into one.

 

[Furka]

No need to create or merge any partition. Only make the format from your root CT10000... unit. That's all.

 

[ColdShadow]

No need to create or merge any partition. Only make the format from your root CT10000... unit. That's all.

The above picture is after I formatted the top drive (CT10000),it still created those two container disk2 and untitled within itself.

 

[k-hawinkler]

I am using macOS Mojave, Catalina, and Big Sur each on its own separate SSD.
I have used Mojave's Disk Utility to format new SSDs first with HFS+, then with APSF if so desired.

When I boot from the internal Mojave SSD I get the following message:

"Incompatible Disk
This disk uses features that are not
supported on this version of macOS"

Also APFS boot SSDs appear twofold on the desktop, for example Catalina as:

T7_APFS_Catalina
T7_APFS_Catalina - Data

Following is a Big Sur example:

Update
Envoy Pro EX - Data

If Catalina is booted up, only one name appears on the desktop, such as:

Macintosh HD
T7_APFS_Catalina
Update

If Big Sur is booted up, one unmodified name appears, such as:

Macintosh HD
T7_APFS_Catalina
Envoy Pro EX

 

[ColdShadow]

It’s a complete mess,I reformat the drive to APFS and now installer cant even find the drive..what a un-necessarily time and effort wasting process..

I have another computer which is Windows 10 gaming only PC never had so many strange problems.
every issue I can google and find solution in 30 seconds.Big Sur is broken beyond repair.

maybe I should get rid of Mac finally after over 10 years..so much for reliability and issue free operation..this sucks.

 

[Furka]

It’s a complete mess,I reformat the drive to APFS and now installer cant even find the drive..what a un-necessarily time and effort wasting process..

I have another computer which is Windows 10 gaming only PC never had so many strange problems.
every issue I can google and find solution in 30 seconds.Big Sur is broken beyond repair.

maybe I should get rid of Mac finally after over 10 years..so much for reliability and issue free operation..this sucks.

View attachment 1702631

Try to format to Macos File System, not APFS.

 

[gilby101]

I am using macOS Mojave, Catalina, and Big Sur each on its own separate SSD.

I think you are expecting old macOS to understand formats used by future macOS.

BS should successfully mount the Catalina and Mojave boot disks. But neither Mojave or Catalina knows about the changes in structure of BS boot disk.

Refusing to mount a future macOS might be considered a safety feature. Too easy to mess up the structure of a future boot disk.

When running Mojave from internal disk, I would disconnect the externals with Catalina and BS.

 

[IowaLynn]

APFS is "Mac file system." The old file system pre-APFS was HFS+. Which is two decades old.

 

[k-hawinkler]

I think you are expecting old macOS to understand formats used by future macOS.

BS should successfully mount the Catalina and Mojave boot disks. But neither Mojave or Catalina knows about the changes in structure of BS boot disk.

Refusing to mount a future macOS might be considered a safety feature. Too easy to mess up the structure of a future boot disk.

When running Mojave from internal disk, I would disconnect the externals with Catalina and BS.

Well, all 3 OSs are capable of using HFS+ and/or APFS. No problem there.
However you make valid observations about forward and backward looking OSs.
Indeed from Mojave's Preferences Startup Disk panel I can select to next boot up from a Mojave or Catalina boot drive, but not from a Big Sur one. Catalina or Big Sur give me the option to select from all 3 OSs. So I see no reason to disconnect any externals.

 

[Furka]

APFS is "Mac file system." The old file system pre-APFS was HFS+. Which is two decades old.

We will try to solve his problem, nomather if the system HFP+ is old or not. Yesterday. I have downgraded 2 Macs from BS to Mojave, without any problem of disk incompatibility, formatting them from the Mojave USB installer this way. After all, when Mojave installs itself, it reformats to APFS automatically.

 

[ColdShadow]

I finally resolved the issue,first installed the original Mac OS version that the iMac was shipped with (Sierra) via internet recovery,(the drive is now one APFS volume),then update it to Mojave.

It’s definitely a bug and issue Apple needs to resolve.
Also they shouldn’t advertise Big Sur for older Macs,it’s performance is simply not great on many older Macs,there are 100s of complaints online.

so a few here who claim they older machine is running as fast a before,simply don’t notice/remember the difference/ or don’t use their Mac too enough to notice.

Big Sur will NOT run great on 2015 and older Macs.

 

[Spudboy2014]

I have Mojave on an external SSD (APFS). I started to get this error message recently. Cloned my drive and reformatted to MOEJ Guid. Then transfered my data back from the clone drive.

Still get the error message.

I give up. I’m just gonna live with the error message.

 

[veganfox]

I got a 2018 Pro with BS preinstalled, gone back to Mojave when I released half the torrented apps don't work being 32bit, anyway I get this message everytime I restart the computer (this disk uses features that are not supported on this version of macOS). Wish I could get rid.

 

[dsemf]

I got a 2018 Pro with BS preinstalled, gone back to Mojave when I released half the torrented apps don't work being 32bit, anyway I get this message everytime I restart the computer (this disk uses features that are not supported on this version of macOS). Wish I could get rid.

When you went back to Mojave, did you you set the View to Show All Devices and format the top level of the disk drive?

 

[liberians]

HI THERE I DOWNGRADE TO MOJAVE AND I HAVE THAT PROBLEM CAN I LEAVE LIKE THAT CUZ WHEN I UPDATED TO BIG SUR MANY OF MY APPS DOESNT WORK THANKS!!

(this disk uses features that are not supported on this version of macos)

 

[veganfox]

I also get these. Any ideas to resolve? Much appreciated

 

[veganfox]

When you went back to Mojave, did you you set the View to Show All Devices and format the top level of the disk drive?

Yes and had to download Mojave to an external drive and boot/install from the beginning. It wiped everything which is what I wanted, but now it's clearly not optimal, although everything works fine. Still can't find any Adobe CS's to work properly

 

[Gsazraetr]

As others have described, this "disk uses features that are not supported" warning appears even if the two installs are placed on separate partitions (i.e. different APFS containers).

I am aware I can get rid of it if I remove the partition with the Big Sur volumes on it. I was just wondering if anyone knew of a way to simply prevent it from appearing when booting into the older OS.
I've tried multiple times to switch to Big Sur but keep reverting to Mojave. I just want to be able to use the above described dual-boot setup in peace.