How to fix the 'First Aid found corruption that needs to be repaired.' error?

One way in which the "First Aid found corruption that needs to be repaired. To repair the startup volume, run First Aid from Recovery. Click Done to continue." message may appear is when Mac users attempt to check their startup disk using First Aid. The other way is when a MacBook won't turn on while a loading bar is frozen on the screen.

Here are three ways to fix the "First Aid found corruption that needs to be repaired" issue.

Before you format your disk, you can use iBoysoft Data Recovery for Mac in Recovery Mode to get back your data, which is powerful recovery software for corrupted hard drives and capable of retrieving lost data from external hard drives that First Aid failed to repair. Here's how:

After that, back up your data on your Mac and reformat your disk so that you can use your external hard drive normally.