How run Disk Warrior on APFS (High Sierra)?

Wait for Alsoft. If your data is not backed up, Prosoft Data Rescue, iSkysoft, and Subrosasoft all offer data recovery that works on systems that are not mechanically failing. iSkysoft preserves folder structure too.

Once your data is recovered, you can also get Micromat Techtool Pro to try to repair your hard drive structure if it is APFS aware.

But APFS is a different file system from HFS+, and you shouldn't use a tool meant for one file system on another.

The problem is that Apple hasn't released the necessary APFS documentation for the third party utilities to properly repair an APFS volume. I did try out Tech Tool Pro since my supervisor bought it for us, but I would not recommend it. We used to use it back in the OS9 and early OSX days and it was "ok", but I personally wouldn't recommend it now. I was very underwhelmed by it.

The best thing to do if you are using APFS is to make sure to have frequent regular backups in case you need to erase the drive to create a clean APFS volume.

I do recall that someone had an easy way to modify the macOS 10.13 USB installer so that it would allow a volume to remain as HFS+ instead of being converted. It may have been an option with the "createmediainstaller" utility and if it was I think Apple may have removed the option in later updates.

I'm on 10.13.6, but have thwarted the ability of it to change my SSD to APFS, would see if I could pull that off with Mojave if I thought it wasn't a downgrade. Other Macs with 10.13.6 have no SSDs, boot time is the only diff if you have plenty of RAM.

Thanks. I concur. If everybody had done that or remained on macOS Sierra, Apple would have released the full APFS documentation time ago, and we would have DiskWarrior 6. Hopefully, that will not be much delayed now, since APFS was announced/released by June/September 2017, almost three years ago!!!

This is from the horse's mouth (what Alsoft says in their Twitter account), in relation to when Apple will release the required APFS documentation: "…it does seem that the file system is a work in progress with documentation still changing. Time Machine 2 is a likely target".

So, hopefully, Apple will announce Time Machine 2 with macOS 10.16 on 22nd June at WWDC 2020, which should set APFS final (or so) specifications, Apple releases documentation about how to write to APFS and DiskWarrior 6 to rebuild the directory of APFS disks is finally released, after three years of APFS being released by June to September 2017. Just about time!

You should be backing up your data regardless. Disk Warrior just improves the efficiency of the file system and offers data recovery functionality. But you should backup with either Time Machine or Carbon Copy Cloner. Look also at Carbonite.

I never let Apple update me until DiskWarrior has a version for that OS. :)

BDAqua, does it mean that you are in macOS 10.12 Sierra, since newer versions have APFS and DiskWarrior cannot rebuild their directory?

Well, we might never see it,Apple is closing off what Apps are allowed to do & the next OS due shortly will severely limit access to everything. :(

Thanks.