How to Skip Converting to APFS When Installing macOS High Sierra

Oct 17, 2017 - 20 Comments

How to skip APFS when installing macOS High Sierra

MacOS High Sierra includes the all new APFS file system, which is arguably one of the most significant new features introduced in the new Mac operating system update. Nonetheless it’s possible that some Mac owners with SSD volumes will want to not convert the existing HFS+ file system to APFS file system when installing macOS High Sierra. With a little command line magic, you can skip converting to APFS during the macOS High Sierra installation process if desired.


How to Install macOS High Sierra Without Converting to APFS File System

This is not recommended and should only be applicable to advanced users who have specific reasons to not want to convert a Mac to APFS. APFS is faster and offers better encryption, amongst other benefits, so it’s generally recommended to use APFS if the Mac supports it. APFS is currently only supported on SSD drives, with Fusion drives support for APFS soon to arrive in a future Mac software update.

How to Not Convert to APFS During macOS High Sierra Installation

By skipping APFS conversion of file system, macOS High Sierra will install with the longstanding HFS+ file system instead.

  1. Download the MacOS High Sierra installer from the App Store as usual, making sure it’s within the /Applications/ directory*
  2. Open the Terminal application, found in /Applications/Utilities/ (or from the Utilities screen menu options if booted from a USB boot installer)
  3. Enter the following command syntax at the command line prompt:
    /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/startosinstall --converttoapfs NO

  4. Hit return key to start the macOS High Sierra install process with the –converttoapfs NO directive, thereby skipping the APFS conversion of existing file system

* You will need the full installer to have the Contents/Resources/ options available to you. You can download the full macOS High Sierra installer with these instructions if you’re getting the little mini-installer without /Content/Resorouces/ folder.

In case you were wondering, skipping APFS can be achieved when running the High Sierra installer directly from Mac OS or when using a macOS High Sierra boot installer drive.

Mac users who ran the beta of macOS High Sierra may remember earlier versions of the beta builds had a toggle setting during installation to skip APFS conversion, but that option toggle is no longer available in the installer.

Regarding APFS and macOS High Sierra, Apple says the following on a knowledge base support article:

“When you install macOS High Sierra on the Mac volume of a solid-state drive (SSD) or other all-flash storage device, that volume is automatically converted to APFS. Fusion Drives, traditional hard disk drives (HDDs), and non-Mac volumes aren’t converted. You can’t opt out of the transition to APFS.”

Despite the Apple support article saying that you can’t opt out of the transition to APFS, it turns out that you can skip APFS if you choose to start the installer from the command line of Mac OS and give a directive to skip file system conversion. Outside of using the Terminal approach outlined above, or installing on an HDD or Fusion drive, there is no known other method to skip APFS.

Again, there is no benefit or particular reason for most users to skip APFS conversion. Skipping APFS file system on a Mac with a flash drive means the computer won’t see the potential performance boost offered by APFS with High Sierra. This is really only for advanced users who need to skip APFS for a specific reason, usually for networking or drive sharing compatibility purposes.

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Posted by: Paul Horowitz in Command Line, Mac OS X, Tips & Tricks

20 Comments

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  1. Mikolaj says:

    The reason might also be that the apsf cannot be installed on a raid0 volume.

  2. David says:

    What happens if you have your disk partitioned so you can dual boot two different version of your operating system, eg, Yosemite and High Sierra? Does the Yosemite partition remain HFS?

    • junebeetle says:

      Yeah, just like you can have a HFS+ and FAT32 or NTFS or whatever on the same drive, you can have an HFS+ and APFS partition as far as I know.

  3. Dori says:

    I am not a “nerd” and I do not understand what will happen to my backups online or on hard drives (not SSD) if I install High Sierra. Will those drives be readable and writable? or not? and if not, what do we do? I’d like to see an article that is easy to understand for all of us non-techie types. Thank you.

  4. Other reasons include all users of Adobe Illustrator which goes fubar on APFS. There is likely more essential software which is prohibitively incompatible.

  5. vdiv says:

    Why is any performance boost with APFS “potential” at this point? What factors determine performance improvements or degradation by converting to APFS?

    Also some folks have disk utilities that do not work with APFS (due to lack of detailed documentation on it from Apple), that’s a good reason to skip it for now.

  6. John F says:

    My Mac volume is a conventional HDD, so obviously APFS won’t install there. However, I have a couple of external SSDs which I connect to the Mac from time to time. When (and if…) I get round to installing High Sierra, will these drives be forced to change to APFS format ? Presumably that would render them unreadable by a non-High Sierra machine ?

  7. Liam says:

    “usually for networking or drive sharing compatibility purposes” …this is likely many Apple users!

    Why would anyone want to make their network of Apple devices ( of various vintage ) plus all of their external drives etc. suddenly STOP working together? I’m staying with Sierra for the foreseeable future on my MBP TB, though I have installed High Sierra onto a 2008 Mac Pro with great success using the macOS High Sierra Patcher Tool .

  8. bogchop says:

    I’ve tried this command, but I get the following error after putting my password in: “Error: could not find target…”

    Any ideas? Downloaded HS directly to my Applications folder via the App Store. I’m avoiding APFS because I have a RAID0 SSD setup, which HS refuses to install on directly :(

    • Paul says:

      You may need to specify a target hard disk if the target can not be found. Try that with the –volume flag like so, assuming “DestinationDriveName” is the name of the drive

      startosinstall --converttoapfs NO --volume /DestinationDriveName

      So the full command with path name to /Applications/ installer would be like:

      /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/startosinstall --converttoapfs NO --volume /DestinationDriveName

      If the volume is located elsewhere and is not the root, just specify the exact path:

      /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/startosinstall --converttoapfs NO --volume /Volumes/DestinationDriveName

      Let us know if that works for you.

      You also might want to search around and make sure people have reported good experiences with RAID setups and APFS and High Sierra with similar configurations. Backup first!

      • justink says:

        after all that I get something that says

        arguments:
        –application path
        –licenses etc.

        and at the end it says “example startosinstall –converttoapfs YES”
        it even mentions it earlier but wont proceed past this arguments thing.

  9. bogchop says:

    Thanks Paul, will give that a shot. The entire reason I’m going this path is that I know APFS was disabled for RAID0 setups on SSD. I assume that HFS+ still works the same, and has been working well on Sierra (and previous incarnations) for a long time. I renamed my boot volume to “SSD”, so guessing it would be “–volume /SSD” for the install?

    I’m one of those Mac Mini users who replaced the 2x500GB mechanical drives for 2x500GB SSD’s, and went RAID0 for speed/partition size :)

  10. bogchop says:

    Tried adding the –volume argument with ‘–volume /Volumes/SSD’ but it just returns the entire Arguments listing – doesn’t look like I can actually specify a path! Damn it :(

  11. Jack says:

    Yeah, I am getting the same issues as bogchop.

  12. Jack says:

    I also noticed that the MacPro (5,1) needs a firmware update. Question ? – Before installing 10.13, should one first update the firmware (via a separate drive) and then attempt the RAID 0 installation?

  13. Jason says:

    A good reason for switching (for now):
    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81797

    In AFPS’s defense, Apple claims their new file system demonstrates bugs in GCC’s make sub-system. But that system has been in place for years (like 20). So who’s to say who’s wrong. Apple and GCC are big players that probably will not except blame for a while. So…

    Switching to HFS+ for now.

  14. Eshant Gupta says:

    Boot macos install is not created in my case. FakeSMC already placed in Other dir

  15. Jarno says:

    Bootcamp is not working properly on APFS MacOS. Fron MacOS High Sierra you can enter windows using bootcamp, but the other way around isnt possible. Windows doesnt see the APFS disc. Shutdown and restart ALT is still working but is not ideal

  16. Kody says:

    We are trying to mass image with High Sierra and we want to add the “Don’t convert” flag to the automated installation. How do I go about doing this?

  17. Henk says:

    Another minuspoint: photoslibrary won’t copy to HS if coming from hfs+ casesensitive (El Capitan). (You won’t find out but after copying 13G of the 80)

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