One of the notable features of macOS High Sierra is the introduction of the APFS file system. APFS is a modern file system that replaces the extraordinarily aged HFS+, introduced in 1998. For reference, here’s a quick overview of the APFS features.

APFS Performance on macOS High Sierra

APFS will enable lots of new technologies on your Mac.

When the public beta of macOS High Sierra is released, you’ll likely have the option to stay with the old HFS+ or elect to upgrade your boot drive to APFS. Because Apple has had stunning success with APFS in iOS so far, you’ll probably want to upgrade your Mac to APFS, especially if your boot drive is Flash-based.

Here’s a screenshot of the installer. Note the checkbox circled in red.

High Sierra (Beta) installer showing the APFS upgrade option

High Sierra (Beta) installer with checkbox for APFS.

What’s mildly tricky here is that the description of APFS, at the bottom  in the smaller print, is isolated from the checkbox above the disk icon. I’ve seen several instances in Apple’s forum where people forgot to check the box before a hurried click on the Install button.

If that happened to you, there’s a fix to upgrade to APFS after your installation is done. The upgrade is non-destructive—you won’t lose any files.

The macOS High Sierra Post-Install Upgrade to APFS

1. Of course, compete the installation in the normal fashion. If the upgrade to High Sierra seemed normal, continue to step #2.

2. Restart the Mac into Recovery Mode. To do that, select Restart from the Apple menu and hold down the Command and “R” keys (often abbreviated as CMD+R) until you see the Apple Logo or a spinning globe. You’ll be dropped into the macOS Utilities.

3. Launch Disk utility. Click-select your named boot volume. (Not the physical drive above it.) In this example, it’s called “John’s-MacBook.”

4. In the Disk Utility Edit menu, select “Convert to APFS.” (It will be dimmed if you didn’t properly select the boot volume.)

Disk Utility Edit menu showing the Convert to APFS option

Disk Utility > Edit > Convert to APFS

5. You’ll get a confirmation dialog box. “Would you like to convert Your-drive-name to APFS? The box notes: “APFS volumes cannot be used with older versions of macOS. Converting to APFS cannot be undone.” Click on the “Convert” button.

6. When the conversion starts, you’ll see a progress indicator with all the geeky details if you elect to show them. Click Done when that button becomes undimmed.

APFS conversion progress on MacBook SSD

APFS conversion progress. It goes fast.

The results of the conversion will be reported to Apple for QC analysis. This is okay to allow.

The size of the SSD in my MacBook is 256 GB. It took approximately two minutes in my case. That’s fast, and it’s just another indication of the brilliance of Apple’s APFS team.

If you’d like the warm fuzzy of seeing that the drive was converted, on the Mac’s desktop, click-select the boot drive icon. (If you don’t see it, you may have to reveal it with Finder > Preferences > General) Then hold down the Command key and type “I” (CMD+I) for “Get Info.” You’ll see something ike this:

Get Info for Mac's boot drive showing APFS format

Get Info for an APFS volume.

If you’d like to read more about the features of APFS, I also recommend these other publications. “APFS: What You Need To Know About Apple’s New File System.” and “10 Things You Should Know About APFS; Apple’s New File System.” Some of the discussion in these articles refers to iOS, but it’s all the same file system in iOS and macOS.

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“Convert to APFS” is dimmed for my Internal Drive “Memory Alpha” (CoreStorage Logical Volume) on my MacBook Air running 10.14.3. How do I “properly select” it? I apparently have the option to Mount the drive, and it is encrypted. I am also showing an OSX Base System drive.


Thanks for sharing this fantastic blog, really very informative. Your writing skill is very good, you must keep writing this type of blogs. alexa customer service

Does this method wipe the SSD drive data? thanks.

Thanks, worked for me! In fact the last few iOS updates to my MBP could not be done because they required APFS. Thought I was left behind in the dust because I went NVMe instead of SSD. All good now!


This is really a concerned topic of MAC when I “unmount” the drive first; then the option to “Convert to APFS” was available so keep take attention at this. There is also sometimes Firefox Not Responding error on our Pc or lappy you can contact us.

Roger A. Careaga

I unmounted the mac SSD drive and clicked on “Convert to APFS”. It started fine, then said it was “Opening and closing disk3s2 to terminate old content driver” and the infamous beachball started spinning. It has been that way for 20 minutes now.

You helped me

On step #4 above … in the Disk Utility Edit menu, my “Convert to APFS” is dimmed and it doesn’t matter that I properly selected the boot volume. Any ideas why?

When I initially was installing High Sierra beta 1, I tried three times and each time it crashed until on the 3rd attempt, I chose not to convert to APFS and that is when the installation actually was successful.

P.S. Yes, I did have FileVault encryption turned on during the High Sierra install attempts. Does that make a difference?

Well, I think I was successful in doing a APFS conversion. I had to “unmount” the drive first; then the option to “Convert to APFS” was available. After the conversion, the internal drive was automatically mounted again. Hope this helps others.


@sterlingma1 — I had exactly the same issue (on an external hard drive.) I think I saw somewhere else that APFS isn’t supported yet in some configurations. I’m having trouble finding details of when it is supported though.


Awesome. The non-destructive upgrade is great!


I had created a separate partition on my Mac called BETA. Then installed original Sierra on BETA partition. Then installed new Public Beta of High Sierra on BETA. I never saw the option to use APFS. So I then followed your instructions to Convert to APFS. Following this process, I could not boot to the BETA partition. I had to get some Terminal commands from another site to delete the volume. I have since recreated BETA, installed High Sierra. Still never saw the check box for installing as APFS. Any ideas?