Running First Aid on Apple disk image media

999North Said:

"Can I use the computer with this error? or what is the recommended next step?: thanks"

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Reinstall the macOS:

The volume is apparently corrupt. So, reinstall the macOS. Nothing would be lost. It's just that misplaced items would be placed back to where they should be and corrupt system files would be replaced by clean files. Go Here: Reinstall macOS - Apple Support. Prior to the reinstallation, to prevent data loss, be sure to back up your Mac with Time Machine, so that you can have something to restore your Mac from, should anything happen after the reinstall.

Hi 999North,

The macOS Base System image is macOS Recovery itself, not your actual startup disk.

Your internal drive should have a name that is something similar to "Apple HDD" or "Apple SSD".

Also, in Disk Utility, click View -> Show All Devices to be sure that you're seeing all available devices.

@Encryptor5000 is entirely correct. To add to @Encryptor5000's post you can run First Aid on the physical drive, but you probably want to really run it on the hidden Container which can be revealed with the instructions @Encryptor5000 provided to reveal the physical drive. If you don't see a physical drive, then the drive may be bad or it may indicate a third party SSD is installed and you need to boot from macOS 10.13+ (which ever operating systems are supported by your specific Mac 10.13 - 12.x) in order to see the physical SSD and its volumes.

In general for any .dmg or sparsebundle image file: Do the archive image files open allowing access to the files inside? You really should never need to run First Aid on these files. Besides you if there were any issues, then you should restore any files from a backup made before the archive image file became corrupt.