How to Fix S.M.A.R.T. Error in Mac Devices

Unlike most macOS error codes that are caused by minor software conflicts, a S.M.A.R.T. error on your Mac is a serious alarm bell that demands your immediate attention. If Disk Utility or a third-party app tells you that a drive's "S.M.A.R.T. Status: Failing," your hard drive is telling you — in the most direct way it can — that it is physically dying.

In this comprehensive guide, we will explain exactly what S.M.A.R.T. is, why these errors are critical, and most importantly, walk you through the precise steps you should take right now to protect your data and fix the underlying problem before it is too late.

What is S.M.A.R.T.?

S.M.A.R.T. stands for Self-Monitoring, Analysis, and Reporting Technology. It is a built-in diagnostic system that virtually every modern hard drive (HDD) and solid-state drive (SSD) contains. The drive constantly monitors its own internal health metrics — things like read/write error rates, bad sectors, spin-up time, temperature, and overall wear — and reports them to the operating system.

When macOS (via Disk Utility) reports a S.M.A.R.T. error, it means the drive's own internal sensors have crossed a critical threshold, predicting imminent failure. This is not a software glitch. This is the drive's hardware engineering explicitly raising a red flag.

Step 1 (URGENT): Back Up Your Data Immediately

Do not troubleshoot. Do not try to repair the drive. The absolute first thing you must do upon seeing a S.M.A.R.T. error is create a backup of every important file on your Mac. Every minute you delay increases the risk of losing irreplaceable data.

Option A: Time Machine Backup

1. Connect an external hard drive to your Mac that is at least as large as your internal drive's used storage.
2. Open System Settings > General > Time Machine.
3. Click Add Backup Disk, select your external drive, and click Use Disk.
4. Click Back Up Now and wait for the backup to complete fully. Do not interrupt it.

Option B: Carbon Copy Cloner or SuperDuper!

For a failing drive, a bootable clone is even safer than Time Machine. Apps like Carbon Copy Cloner or SuperDuper! (both have free trial versions) will create an exact, bootable duplicate of your entire drive on an external disk. This means if your internal drive fails tomorrow, you can plug in the clone and continue working immediately.

Step 2: Verify the S.M.A.R.T. Status in Disk Utility

Once your backup is secure, verify the S.M.A.R.T. warning using Apple's built-in Disk Utility.

1. Open Launchpad, type Disk Utility, and open it.
2. In the sidebar, click on your internal drive (usually "Macintosh HD" or "Apple SSD").
3. Look at the bottom of the Disk Utility window for a line that reads S.M.A.R.T. Status.

The status will read one of three things:

• Verified: Drive is healthy. The S.M.A.R.T. error may have been a false positive from a third-party app.
• Not Supported: The drive (usually an external drive) does not report S.M.A.R.T. data over its connection type (e.g., USB).
• Failing: The drive has crossed a critical health threshold. Replacement is urgently needed.

Step 3: Use a Third-Party App for a Detailed Report

Disk Utility only shows a simple "Verified" or "Failing" status. To understand exactly which health attribute is failing, you need a tool like DriveDx or Hard Disk Sentinel. These apps read all of the raw S.M.A.R.T. attributes and tell you, for example, whether it's bad sectors, a heating issue, or reallocated sector counts that are triggering the warning.

While this detailed report won't fix the drive, it helps you understand the urgency. A drive with a single reallocation event might last weeks; a drive with hundreds of bad sectors could fail today.

Step 4: Replace the Drive (The Only True Fix)

It is critical to understand: you cannot software-patch a failing hard drive. No app, no Disk Utility repair, no Terminal command will fix a physically failing drive. The S.M.A.R.T. warning means the hardware itself is deteriorating.

Your options for replacing the drive depend on your Mac model:

• Older iMacs, Mac Minis, or Mac Pros (pre-2019): These often have user-replaceable or service-replaceable drives. A qualified technician can install a new SSD for a relatively affordable cost.
• MacBooks (2012-2017): Depending on the model, the SSD may be replaceable, though it often requires specialized tools. iFixit.com has detailed guides for your specific model.
• Modern MacBooks and iMacs (2018+): Apple solders the SSD directly to the logic board on newer models, making DIY replacement impossible. You will need to use Apple's service program (AppleCare+ if you have it) or a certified Apple Service Provider.

Step 5: Restore from Your Backup

After the new drive is installed, you can restore your data from the Time Machine backup or bootable clone you created in Step 1.

Restoring from Time Machine:

1. During the macOS setup process on your new drive, you will be given the option to "Transfer Information to This Mac."
2. Select "From a Time Machine backup" and follow the prompts to restore everything from your external backup drive.

Booting from a Clone: Simply plug in the clone drive and hold Option while starting your Mac to boot from it temporarily while you migrate to the new internal drive.

Conclusion

A S.M.A.R.T. error is not a bug to be fixed — it's a hardware death notice to be acted upon. The priority sequence is always: back up first, verify with Disk Utility, then plan your drive replacement. Every moment you wait after seeing a S.M.A.R.T. "Failing" warning is a gamble with your irreplaceable data.