Error message: macOS can’t repair the disk

If you got an error message like the one above, it is often caused by one of two things: either your drive is going bad or the drive got disconnected in the middle of a vital change and now your computer no longer trusts the contents of the drive.

If it’s a drive that has gone bad you will want to replace it right away. DriveDx is a great tool for finding that out. Though the utility is a little fussy with external drives so if you are a customer of mine you might want to book an appointment.

If it just got disconnected at the wrong time and the data is a little scrambled, you will need to erase the drive using Disk Utility and set up Time Machine again if it’s a Time Machine drive. The good news here is that if you set up the drive again using Apple’s new disk format, APFS, my experience is that APFS is much more reliable so you are less likely to have this problem again. APFS drives are only supported for Time Machine on macOS 11 Big Sur and later. Unfortunately, a healthy Time Machine cannot be converted to APFS. You must erase your backup drive with the new format and set it up again.

In either case, If it’s a Time Machine backup drive, your new drive or newly erased drive will not have your prior backup history. In other words, if you deleted a file a month ago and you erase the backup drive, that file will be permanently gone. But anything that is on your computer at the moment you set up Time Machine again, even if it is a file you haven’t touched in years, will be part of the new backup.

This really isn’t something most people will want to tackle without a little guidance from a professional who can talk through your options. If you are one of my customers I suggest you book a remote appointment with the button below.

Further help

If you are an existing customer who needs help with this or if you have other questions, or if you are in San Francisco and interested in becoming a client I invite you to book an appointment with me. Otherwise, you may wish to contact Apple Support or find a local Apple consultant.

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