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First Aid failed with 'File system check exit code is 8' on 2012 iMac Fusion Drive

My iMac (Fusion Drive) keeps crashing at startup. When I turn it on, it shows the Apple logo and the progress bar. But when the progress bar completes, it shuts down again. Pressing the power button just brings back the same loop. I then ran First Aid in macOS Recovery to repair Macintosh HD and the OS X Base System. The repair failed with the following details: File system check exit code is 8. Restoring the original state found as unmounted File system verify or repair failed. Operation failed...

Best Answered by

Jenny Zeng

Answered on Tuesday, August 27, 2024

The error "File system check exit code is 8" indicates file system corruption on your Fusion Drive. To repair your Fusion drive, you need to reset it.

Remember to recover data from your Mac in Recovery Mode before proceeding, as the repair process will erase all data on the drive.

  1. Boot into macOS Recovery.
  2. Select Utilities > Terminal.
  3. Type the following command and hit Enter.diskutil resetFusion
  4. Type Y and hit Enter when prompted for a confirmation.
  5. Quit Terminal when the reset is complete.
  6. Click "Reinstall macOS" and follow the instructions to finish the installation.