APFS Overallocation Issues and Remediation

by: Loner T

Last modified: Feb 18, 2021 9:44 PM

0 1719 Last modified Feb 18, 2021 9:44 PM

macOS High Sierra (10.13) and later use APFS as the default File System (About Apple File System). Some of the file system issues can be addressed using Unix fsck_apfs command. High Sierra does not have the same capabilities as Mojave (or later) does. If you are on High Sierra, and do not want to upgrade to Mojave, the following procedure can work if Mojave is installed on an external disk (How to reinstall macOS from macOS Recovery - Apple Support). Do not use an older fsck_apfs on a newer macOS version.

To run fsck_apfs, Start up your Mac in single-user mode or verbose mode - Apple Support and run

fsck_apfs -s -o -y /dev/rdisk1

and post a photo of the output. Be aware that there is no scrolling in terminal in this mode.

You may need to use Command+S, if your model does not support the new method. See the footnote in the linked article.

An alternative for newer Macs is to use Internet Recovery, unmount the APFS Container, and run the fsck_apfs on the unmounted APFS Container.