Upgrading to Catalina shows “file system check exit code 8.” Disk repair and Safe Mode didn’t work. Restored via Time Machine to another iMac—no error. Restored back—error persists. How to fix it?
Have you tried repairing the file system using Terminal? If you’re using an Intel-based Mac, you can manually run the fsck command in Single User Mode:
- Turn on your Mac and immediately hold down Command + S to boot into Single User Mode (you’ll see a black screen with white text).
- Once the command line finishes loading, type the following command and press Enter:
/sbin/fsck -fy - If any issues are found, fsck will attempt to repair them. If you see a message saying “The volume was modified”, run the command again until you get “The volume appears to be OK.”
- Finally, type reboot and press Enter to restart your Mac.
The simplest and quickest way to fix the issue is to erase the disk and perform a clean installation of macOS. However, this process will delete all your data, so it’s strongly recommended to recover your important files first.
I’ve previously used iBoysoft Data Recovery for Mac, which has a very high recovery success rate. With just a few clicks, you can easily retrieve your lost files.
Once your data is safely recovered, follow these steps to format the disk and reinstall macOS:
- Restart your Mac and immediately press Command + R to enter macOS Recovery Mode.
- Open Disk Utility, select your system disk (usually named Macintosh HD), and click Erase.
- Return to the main menu and select Reinstall macOS, then follow the on-screen instructions.