2015 21 inch iMac with Mojave: FS is Journaled HFS+ instead of APFS. Now I cannot change the FS to APFS nor upgrade the OS.

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2015 21 inch iMac with Mojave: FS is Journaled HFS+ instead of APFS. Now I cannot change the FS to APFS nor upgrade the OS.

I'm new to Macs and am trying to help a client.

Her iMac is in a Catch-22: I cannot format the disk as APFS (Even though when Mojave was originally installed, before she bought the machine, it should have implemented APFS but did not); I cannot upgrade to a modern APFS OS either.

I tried Disk Utility but the APFS option is greyed out, which according to an Apple support post means there is a problem with the disk; I tried unmounting the disk and using DU to do it but same result; I tried upgrading the OS, but it just says "File System Not APFS" and stops.

I ran First Aid, and it found no problems.

The OS is Mojave 10.14.6; the hardware is Intel Core I5 with 16GB of RAM. (If it's not Apple M1, does that make a difference?) The HDD is a SATA 1TB.

The system was bought on EBay; it sat unused for some time.

Is there any way out or any way to format the disk as APFS? Do I need to format it then install a modern Mac OS from a bootable USB?

Also, does journaling have anything to do with it? Do I need to shut it off first? TIA.

Earlier Mac models

Posted on Jun 27, 2023 9:43 PM

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Answer 1

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Jack-19

Level 8

46,266 points

Jun 27, 2023 10:06 PM in response to jksocal

Hi there!

The latest version of macOS compatible with her iMac is macOS Monterey, available here: How to download and install macOS - Apple Support. Is the Monterey installer not allowing installation to proceed due to the disk not being APFS?

If so, you'll need to erase the disk, then install macOS Monterey. To begin, make sure you have a backup of the Mac to restore from. Then, take a look at Create a bootable installer for macOS - Apple Support, and follow the steps for Monterey. Once booted from the USB and in Recovery, choose Disk Utility, and click Continue. When erasing the Mac, select "View" > "Show All Devices" in Disk Utility and erase the main drive. Its name will end in "Media". Make sure this information matches:

Name: Macintosh HD

Format: APFS

Scheme: GUID

Click Erase.

After erasing the startup disk, reinstall macOS.

Let us know if that works!

Jack

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Answer 2

dialabrain

Level 10

136,379 points

Jun 27, 2023 10:05 PM in response to jksocal

See this article: How to reinstall macOS - Apple Support

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Answer 3

Jun 27, 2023 10:36 PM in response to jksocal

jksocal wrote:

Also, does journaling have anything to do with it? Do I need to shut it off first? TIA.

Journaling is about protecting the integrity of the filesystem if the disk is improperly disconnected (e.g., due to someone unplugging an external drive without ejecting it first; or due to a power failure). You typically want this enabled on a HFS+ (Mac OS X Extended) volume.

If you're trying to erase the internal drive, you need to be booted from another drive – whether the internal drive currently is formatted as Mac OS X Extended (Journaled) or not.

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Answer 4

Jun 27, 2023 10:40 PM in response to jksocal

jksocal wrote:

The OS is Mojave 10.14.6; the hardware is Intel Core I5 with 16GB of RAM. (If it's not Apple M1, does that make a difference?) The HDD is a SATA 1TB.

It might make a difference as far as some of the security hoops you would have to jump through to boot off of an external drive.

If you select About This Mac in the Apple () menu, the system will tell you the hardware model name, including the year or time of year when the model you have first came out.

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2015 21 inch iMac with Mojave: FS is Journaled HFS+ instead of APFS. Now I cannot change the FS to APFS nor upgrade the OS.

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