“At lease one of your computer’s internal disk devices must be solid-state”

Seems correct for me.

The Flash Storage should be the SSD.

I still recommend you to run the first script to confirm what disk devices you have inside your computer.

The second command, diskutil apfs list, should list all your APFS containers and volumes, and which disks are used by the container.

Yes.

I was trying to fix my split fusion drive following these instructions:

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

These steps were fine:

• 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.
• When you see the macOS Utilities window, choose Utilities > Terminal from the menu bar.
• Type diskutil resetFusion in the Terminal window, then press Return.

But then this script appeared: “At lease one of your computer’s internal disk devices must be solid-state”.

And I'm not sure what to type. The proposed "Yes" in the instructions does not work...

Thank you so much for your response.

I will have to try running this later, as I'm working now.

It's clear there is some kind of problem with my drive (see the photo - there are two). I recently did a factory reset and this seems to have created this duplicate drive.

The reason it's a problem is that I now get error messages about not having enough memory to support apps. Apple asks me to force quit while I'm in a Zoom meeting as an example.

I assume you didn't mean to reply to me.

Ahh. So is this correct then? Or should it be a "Fusion drive"?

It's the first time that I've seen two drives... but if it's fine, then great!

Then implies that any of the disks you are trying to use is not SSD.

To be sure you are using the right disks, try this command on Terminal

$ diskutil list|grep '/dev.*internal'|awk '{print $1}' |while read d; do echo "$d -> $(diskutil info "$d"|grep 'Device.*Name')"; done
/dev/disk0 ->    Device / Media Name:       APPLE SSD AP1024M

As you can see, this machine has only one SSD storage unit.

:) This is an example of the output you can have when executing the script above.

My iMac is off and packed at this time. I used my MacBook Pro to run the scrip so give an idea what you can expect.

You should have more than one disk.

From the error message you published, implies that neither of your disks are SDD.

So, my suggestion is to run the script above to confirm that you have the right disks on your command.

Hold your horses.

These are volumes created by macOS, over an AFP container.

The Macintosh HD volume is where the OS is installed.

The Macintosh HD - Data volume is where all the user data and apps are installed.

You cannot use those volumes for your Fusion Drive.

You need to use the underlying physical devices to build your Fusion Drive.

For example, on my computer:

• the underlying device is disk0 (Physical Store).
• disk1 is the APFS container.

 % diskutil apfs list
APFS Container (1 found)
|
+-- Container disk1 B9454CD5-5936-4B40-84CB-14426554463B
    ====================================================
    APFS Container Reference:     disk1
    Size (Capacity Ceiling):      1000240963584 B (1.0 TB)
    Capacity In Use By Volumes:   954840313856 B (954.8 GB) (95.5% used)
    Capacity Not Allocated:       45400649728 B (45.4 GB) (4.5% free)
    |
    +-< Physical Store disk0s2 2222A57C-2E8D-47AB-A230-D6475A56D5C1
    |   -----------------------------------------------------------
    |   APFS Physical Store Disk:   disk0s2
    |   Size:                       1000240963584 B (1.0 TB)
    |
...
+-> Volume disk1s6 B5C985EE-CB4D-4A72-A2CE-8FCB430967E8
    |   ---------------------------------------------------
    |   APFS Volume Disk (Role):   disk1s6 (Data)
    |   Name:                      Mac OS X 10.16 - Data (Case-insensitive)
    |   Mount Point:               /Volumes/Mac OS X 10.16 - Data
    |   Capacity Consumed:         3592626176 B (3.6 GB)
    |   FileVault:                 No (Encrypted at rest)

A fusion drive is a mixture of SSD and HDD (Mechanical disk)

Where and how exactly did you receive this message?

According to your profile you have a MacBook Air. Fusion drives were never available for "Airs".