We always put a hard drive in the system to store or back up important files, no matter it is an internal hard disk or an external SSD/USB drive. When a hard drive is installed and connected properly, we can easily access the files on it, but what if the drive malfunctions, for example, becomes uninitialized on Mac?
There are multiple reasons for a uninitialised drive on Mac, to solve this, here we list 10 fixes, applicable for both internal and external hard drive. Also, you will learn about how to recover data from an uninitialized hard drive on Mac, no matter it is Apple APFS format or not.
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When an internal or external disk shows up as “Uninitialised” in Disk Utility on a Mac, there are 2 meanings.
For 1st time user of a brand new external hard drive, you will be required to initialize the disk for use, if your Mac shows it as uninitialized when connecting, it means your new external hard drive is not activated and not ready for use, your Mac needs to use its own language to assign a starting value to the variable of this external hard drive. In this case, you just need to follow the instruction from the disk initialization wizard.
For users who have initialized the hard drive before, uninitialized hard drive means your Mac can recognize the disk, but cannot read your disk anymore and deems this risk as not accessible. This is also the main case when talking about uninitialized hard drive on a Mac. This can be caused by different reasons, keep reading to find out how this comes out.
Reasons to cause uninitialized hard drive on Mac may vary, but basically fall into several types. Here are the likely reasons:
To fix uninitialized internal or external hard drive that is caused by different reasons, here we list 10 solutions, you can choose the one according to you need.
But before your disk dies with the data on it, we should extract the data from it first when it is still can be recognized on your Mac. Because it is not guaranteed that an uninitialised disk will be fixed 100% successfully, and the data might be lost forever if anything done wrong, not all of us is tech-savvy after all.
We recommend using Cisdem Data Recovery to rescue your data on an initialised disk, the list of data recovery tools is long, but Cisdem’s won't ever let you down. It is a Mac program enabling users to recover more than 200 types of file from both external and internal storage devices on Mac. It deals with data loss caused by different reasons, like formatting, trash removing, external hard drive file loss, etc.
Free Download macOS 10.9 or later 
Now, you’ve backed up the files on the uninitialized hard drive to a safe place, we can be relieved to fix the uninitialized disk on our Mac, with one of the following solutions.
Your Seagate or WD uninitialized hard drive may be caused by connection issues, you are recommended to ejecting the disk properly first. Right click on the hard drive, and click Eject, you will be able to remove the disk from your Mac safely.
Then reconnect your external hard drive to Mac. If it is a SD Card, you are recommended to remove it from the card reader, then re-plug it to the card reader and connect the reader to your Mac again.
If the problem persists, change a USB port or use another USB cable, to make sure it is connected properly with a good-condition port/USB.
We may connect many wireless accessories or peripherals to our Mac, but sometimes, these peripheral devices just ruin our Mac’s sleekness or create conflicts that possibly makes the hard drive uninitialized on the Mac.
If your Mac is connecting to many peripheral devices that you don’t use for now, remove them safely by going to System Preferences or choose the device to Eject.
When errors happen, no matter it is on your Mac, Windows PC, iPhone or Android phone, you will be recommended to restart your device as the first aid, since restarting is the most magical method to put everything back to normal again.
You just need to click the Apple icon > Restart, and reboot your Mac. Then unplug the (external) hard drive from your Mac, wait for about 10 seconds, turn on your Mac. Finally, plug the hard disk to your Mac again. You can repeat this to check if it works.
If this doesn’t work, you can reboot your Mac in recovery mode and check if the hard drive shows up as initialized in Disk Utility, especially for your internal hard drive, because this helps diagnose and fix the problems of a Mac’s internal storage device. Here is how:
Still fail to make the disk initialized on your Mac by restarting Mac or reconnecting the disk? If you have another Mac, you can connect the external disk to this Mac and check the disk can be initialized on this Mac.
For internal hard drive that cannot be initialized on Mac, you need to take out the disk from the Mac first, then put it into another Mac and check if it can be initialized or not.
As we mentioned in the 2nd part, virus attack may lead to uninitialized disk, no matter there is virus attacking your Mac or not, you can scan virus with an anti-virus program on your Mac to make sure there is no harm from outside, trying to weaken your Mac.
As for anti-virus program, you can try following:
Or if you’ve enabled anti-virus application on your Mac, you are recommended to disable it temporarily, in order to avoid any conflicts with the hard drive.
If the disk itself is faulty, we need to repair it. Disk Utility is the free macOS program designed to manage all devices on a Mac, including both internal and external hard drive. It allows users to view, analyze, partition, repair and erase a drive with ease. Here is how we can use Disk Utility to diagnose a drive and repair automatically:
Surely, you can use an 3rd party disk repair tool to fix this issue if Disk Utility is not helpful in your case, such as TestDisk, Drive Genius.
Have a copy of those files on the uninitialised disk? Then you can re-initialize the disk with data restored from a selected backup. This Restore feature is also built in the Disk Utility tool. However, this action is irreversible, make sure you choose the correct volume to restore from.
If above listed methods all fail to fix your uninitialized external hard drive on Mac, maybe it is time to format it. To format the disk means erasing the data from your disk, but formatting doesn’t mean deleting files permanently, they just become invisible and inaccessible, but still live on the disk until new data overwrites them.
Though we recommend using Cisdem Data Recovery to extract your data on the unintialized disk first, if you decide to format first, Cisdem is also capable of recovering files from a formatted hard drive.
If the uninitialized external hard drive happens just after you upgrade or downgrade macOS, that may be the problem, the working environment has changed. In this case, you may need to reinstall macOS, upgrade or downgrade to original macOS version, get back the files from your external hard drive first, then install your preferred macOS.
A macOS update might remove all the system issues and let a hard drive show up normally.
If this problem happens after a macOS update, you can revert your macOS to the previous version, by using Time Machine backup.
Or, if the issue of uninitialized external hard drive is caused by physical damages of the disk, like loose or malfunctioned small elements in the hard disk, then you should contact the supplier of your hard drive first, especially when your hard drive is still within the expiry date. If you are using Seagate or Western Digital or other famous brands of hard drive, it is quite easy to get contact with their support.
Just visit their official website, grab the contact information and have a call, or find out your receipt and contact as instructed on the file.
Conclusion
If your hard drive is still in its life circle, fix 1 to fix 10 should have worked, but if failed, you just need a new one to replace this uninitialized hard drive. Before disposal, use Cisdem Data Recovery to save the files into your Mac or other storage devices, then buy yourself a new and better external hard drive.
Connie Yu has been a columnist in the field of data recovery since 2011. She studied a lot of data loss situations and tested repeatedly to find a feasible solution tailored for each case. And her solutions are always updated to fix problems from the newest systems, devices and apps.
Peter
The most comprehensive tutorial I have ever seen. Thanks for solving my problem. The other day my Mac seemed to be attacked by virus, then the computer couldn't read one of my USB flash drive as usual. After reading this page, I got it through successfully.