Summary: External hard drive not mounting on Mac means that you can't access data stored on it. This page helps you mount external hard drives, as well as SD cards and USB flash drives, etc. on Mac. Besides, it also helps recover data from the unmounted external hard drives.

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Click Install macOS High Sierra — Quit Install macOS menu item at the virtual machine window top-left corner to quit mac os installation wizard. Then select Disk Utility in macOS Utilities window, click the Continue button. Select the virtual disk in Disk Utility left panel, then click Erase button at the top bar, it will popup a window.

Usually, an external hard drive will appear (aka mounted) automatically on your Mac once you plug it in, and you can access data on this drive. So, it's annoying when you find that your external hard drive is not mounting for the com.apple.DiskManagement.disenter error or not recognized by your Mac, just like the user below.

• Im running Mac OS X Yosemite and just upgraded to Win10. I used to use the Remote Desktop Connection App but after the upgrade to Win10, I couldnt connect from my Mac. I installed Microsoft Remote Desktop and now I can connect to my Win 10 machine with no issues.
• On your Mac, choose Apple menu Shut Down. If you don’t want app windows that are open to reopen when your Mac restarts, deselect “Reopen windows when logging back in.” A Mac is completely shut down when the screen is black. Some computers also don’t show an active power light or have any fan or drive noise.

'I have a 500 GB LaCie external hard drive, formatted as macOS Extend journaled on MacBook Pro 2014 and I have been using it to do Time Machine backups. Now after updating, macOS is not mounting this external hard drive. The main drive is greyed out in Disk Utility and the partition is not showing up. I can't do First Aid as my LaCie external drive does not mount on the MacBook Pro. Any ideas? Thanks!'

Wondering 'why my external hard drives won't mount on Mac'? This post explains the reasons and teachs how to fix this disk problem without losing data.

Recover data from an external hard drive that won't mount?

As long as your external hard drive doesn't have any hardware problem, fortunately, you can retrieve your files with professional Mac data recovery software - iBoysoft Data Recovery Software for Mac with no fuss.

Best External Hard Drive Data Recovery - iBoysoft Data Recovery for Mac

• Recover lost data from unmountable, formatted, inaccessible, unreadable, corrupted external hard drives.
• Supported storage devices: external hard drives, USB flash drives, memory cards, SD cards, etc.
• Supported file types: photos, videos, audio files, documents, emails, etc.
• Suppported Mac OS: macOS Big Sur 11/10.15/10.14/10.13/10.12 and Mac OS X 10.11/10.10/10.9/10.8/10.7.

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Tutorial for external hard drive data recovery on Mac

• 1. Free download and install iBoysoft Data Recovery for Mac on your computer, and then restart your Mac.
• 2. Launch iBoysoft Data Recovery for Mac.
• 3. Select the external hard drive that is not mounting and click Scan button to scan for all lost data.
• 4. Preview the searching results, choose files you need, and click Recover to get them back.
• 5. Have a check to ensure you have got all lost data back.

Note: You need to save the recovered files to another usable drive.

After having successfully restored all data on this drive, you can set out to erase this external hard drive to fix the disk not mounting on Mac issue.

Dos and Don'ts When External Hard Drive Not Mounting on Mac

Before you go further, it's better to know what you can do and can't do.

1. Do not go straight to reformat this not-mounted external hard drive unless you've restored data from it or backed up it before. Reformatting will wipe the data on this disk and cause serious data loss.

2. Do not run First Aid to directly repair the disk if you didn't restore data from it or back up it. Any further operation is very likely to overwrite your original files and make them unrecoverable.

3. Check if you have a copy of a data backup. If not, recover important files from this unmountable external hard drive first to avoid data loss.

Now, let's make the external disk accessible on Mac.

Fix external hard drives not mounting issue on Mac

To access your external hard drive on Mac, try solutions suggested in this part one by one. Hopefully, you'll be able to open this external hard drive on Mac again.

First, try some simple tricks to mount external hard drive on Mac

In case you miss anything necessary, you can first have some basic checks as following:

1. Re-plug your external hard drive to another port or try another USB cable.

A faulty connection, though it is foolproof, might be the key fix if LaCie thunderbolt drive is not mounting, in that users always forget to check if the port is wobbly or if the cable is broken.

2. Try a super slow jam.

Strange but true, some users found that their external will mount properly when they plug it in exceptional slow motion. However, if they try and plug in the external hard drive normally, the Mac doesn't recognize the disk.

3. Check your Finder Preferences.

When your external hard drive does not appear on the desktop, you can open Finder, choose 'Preference' (or press Command +, ) and check 'External disks' both in General tab and in Sidebar tab to show your external hard drive on your Mac computer.

If Mac could not mount the external hard drive on desktop still, let's troubleshoot this issue with the following solutions.

Solution 1: Force mount this external hard drive in Disk Utility

If you can't find the external hard drive on the desktop or in the Finder, you can try to make the disk online manually in Disk Utility (a native disk management tool in your Mac).

Here is how to mount an external hard drive on Mac:

• 1. Click Go at the upper left of your desktop and go to Utilities, then launch Disk Utility on your Mac computer.
• 2. Click on 'Show All Devices' in View option to list or connected drives.
• 3. Choose the grayed external hard drive in the left sidebar.
• 4. Select Mount in the top center of Disk Utility.

However, if you find that your external hard drive is not showing up in Disk Utility (not a single volume but the whole disk disappears), it is very likely that your disk is suffering some physical damage. In this case, you need to send it to a local data recovery service. But if the Mount option is grayed out and you can see this external hard drive in Disk Utility, you can try another solution then.

Solution 2: Repair this unmountable external hard drive with First Aid

The second suggestion is First Aid in Disk Utility if you are unable to mount the external hard drive on Mac. First Aid is a very simple tool that is built in your Mac, and it is able to detect and repair directory damage and other disk errors. You are advised to run the tool more than once to ensure you are receiving a consistent result.

Note that you should recover data from the unmountable external hard drive if without a backup before running First Aid.

Follow the instructions and repair the external hard drive that is not accepted by your macOS or Mac OS X.

• 1. Go to Utilities and launch Disk Utility on your Mac computer.
• 2. Select the unmountable external hard drive on the left sidebar.
• 3. Select First Aid in the top center and click Run.

Solution 3: Reformat the unmounted external hard drive

If your external hard drive still can't be mounted in Disk Utility after you perform First Aid, or if First Aid failed to repair it like the situation below, your drive should have some serious errors like file system corruption.

• Disk Utility can't repair this disk, what do to?

• How to format external hard drives on Mac?

In this case, you need to back up your important data on the external hard drive, such as family photos, valuable work documents, or any other files. If you don't have a copy of a data backup in hand, the above guide can help you recover data from this unmountable external hard drive. And then, you can reformat your exteranl hard drive to make it work again on Mac.

Tutorial to reformat unmountable external hard drives on Mac

• 1. Launch Disk Utility.
• 2. Click the icon of your unmountable external hard drive on the left sidebar.
• 3. Click on the Erase button function on the top of the Disk Utility window.
• 4. Complete the related information (name, format, scheme), then click Erase button to finish reformatting.

After reformatting, your external hard drive will be assigned with a new file system so that you can mount this unmountable hard drive again.

Then, why we can't access the external hard drive on Mac?

Probably, the user above would never know why his MacBook is not mounting the external hard drive. As a matter of fact, this problem could be caused by many factors, such as damaged file system, virus attack, unsafe ejection or any other improper operations.

Here are some common ones.

1. A damaged file system: If your external hard drive is attacked by virus or if you abruptly eject this drive, it's likely that the file system of this disk would be damaged or corrupted. As a result, the operating system is unable to recognize this disk, and the disk will not be mounted or read by macOS.
2. Connection problems: Another reason that hard drive won't mount on Mac could be a dirty or loose connection between your cable, USB-C multi-adapter, Thunderbolt 3, or other connecting ports. A clear, clean, snug and fit tightly connection is the premise of mounting an external hard drive successfully.
3. Hardware issue: Also, problems related to hardware could also make the disk unmountable, especially when your external hard drive has too much bad sectors or have been physically damaged.

Knowledge Base: What does 'Mount' mean on Mac?

Mounting an external hard disk means the macOS gives a mount point (entrance) to read and access information on the hard drive. Information is accessed by the disk file system and partition table. So, it's a necessary step before the operating system can access a disk (including read from and write to).

Therefore, if an externalhard drive won't mount on Mac, it means the system gets into trouble in recognizing the file system or other information of this hard drive.

Conclusion:

If your external hard drive is not mounting on your Mac, don't panic. Most of the time, you are going to fix this disk problem with the solutions above. Moreover, if you worry about data loss when the disk becomes unmountable, you can use iBoysoft Data Recovery to recover your files first. Remember that, no matter what disk problem you meet, you should perform data recovery in case of losing data.

You can't access a Sandisk, Crucial, or Samsung T3 when the external SSD is not recognized or detected by Mac, whether the external SSD was working for a long time or it's a new SSD you bought recently.

However, hard drives not working or showing up issue is so prone to happen even when you unplug the external SSD from the Mac and later on plug in the SSD again. It's definitely frustrating, especially when you have important files stored on it.

How can you fix the unrecognized external SSD and access your files stored on it? You'll find the solutions to fix the unrecognized or undetected external SSD in this post.

• 1. Check the connections
• 2. Reboot your Mac computer
• 3. Check the unrecognized external SSD in Disk Utility
• 4. Repair the unrecognized external SSD with First Aid
• 5. Reformat the unrecognized external SSD without data loss
• 6. Send the external SSD to a local technician

How to avoid data loss when external SSD not recognized on Mac?

As you can't access the important files on your external SSD that not showing up, data loss may happen. To avoid such a frustrating thing occurs, you'd better recover data from your unrecognized external SSD.

Besides, formatting your external SSD is one of the solutions (always the most efficient way) to fix this issue, so, data recovery of your external SSD is very necessary.

If you have a backup of your external SSD, you can skip this data recovery work. If not, you need to use some data recovery software.

iBoysoft Data Recovery Software for Mac is highly recommended here to recover lost data from unrecognized external SSD. It's a free and secure data recovery tool, which can recover lost data from corrupted, formatted, unreadable, and unmountable SSD. This software works on macOS Big Sur 11/10.15/10.14/10.13/10.12 and Mac OS X 10.11/10.10/10.9/10.8/10.7.

Moreover, iBoysoft Data Recovery for Mac supports main storage devices including hard drives, external hard drives, USB flash drives, SD cards, memory cards, etc. and multiple file formats such as documents, audios, pictures, videos, emails, etc.

Tutorial to recover lost data from unrecognized SSD on Mac with iBoysoft Data Recovery for Mac

• 1. Launch iBoysoft Data Recovery for Mac.
• 2. Select the unrecognized external SSD and click 'Next' to scan lost files on the drive.
• 3. Preview the scanning results, choose files we need, and click 'Recover' to get lost files back from the unrecognized external SSD.
• 4. Have a check to ensure we have recovered all lost files.

How to fix external SSD not recognized on Mac?

Solution 1: Check whether the external SSD is properly plugged in

Since all SSDs use SATA interface, so when an external SSD is not recognized by Mac, the first and foremost solution is to check whether the external SSD is properly plugged in. So simply do these checks:

1. Check if the cable is working by connecting the external SSD with a different cable.
2. Check whether your SSD is using SATA Ⅰ, Ⅱ, or Ⅲ so that your adapter/dock/case is compatible with your external SSD.
3. Try a different SATA to USB adapter and make sure it works by plugging in a different drive.
4. Try to connect the external SSD directly to your Mac if it's a type C drive, rather than accessing it via a USB-C adapter.

If the unrecognized external SSD is a Samsung T5/T3 SSD, and you got the 'System Extension Blocked' and 'No Samsung Portable SSD is connected' messages when executing Samsung Portable SSD Software, simply go to System Preferences > Security & Privacy > choose Allow button next to the message: System software from developer 'Samsung Electronics' was blocked from loading.

Solution 2: Reboot your Mac computer

Sometimes, Mac externalSSD not mounting issue is caused by the system issues. But you easily fix them by restarting. The restarting process will refresh your macOS's memory and starts it up fresh, which works efficiently especially when the USB port is busy. Simply choose the Apple menu and click Restart.

If you are interested in, you can learn what happened inside when Mac doesn't recognize an external drive with details.

Solution 3: Find the unrecognized external SSD in Disk Utility

When an external SSD is not showing up on Mac, the most necessary step is to check whether the external SSD can be found in Disk Utility. If the external SSD can be found in Disk Utility, you make sure that the drive doesn't have any hardware problems. But if you can't find it listed in Disk Utility, the external SSD might be physically damaged.

So simply Go > Disk Utility > View > Show All Devices to check the external SSD.

1. If your external SSD is using Windows NTFS format, macOS won't mount the drive in writable mode. To write to an NTFS drive, you need to download a free NTFS for Mac driver.
2. If you have used this external SSD on other computers for some time and now it is unrecognized by macOS, the file system of the SSD is either unsupportable or corrupted, you need to recover lost data from this external SSD and reformat the drive.
3. If you newly bought this SSD and it is not initialized, you can't see the partitions of the external SSD in Disk Utility but receive an error message 'the disk you inserted was not readable by this computer'. In this case, you need to make sure you don't have any data on this drive and then initialize it in Disk Utility by erasing.

Solution 4: Repair the unrecognized external SSD with First Aid

If your external SSD shows up in Disk Utility but not mounted, you can right-click the drive and select Mount menu and then the SSD will show up on Mac. If the Mount button is grayed out or you fail to mount the external SSD, try running First Aid to verify and repair disk errors.

• 1. Launch Disk Utility.
• 2. Choose the grayed out external SSD from the left sidebar.
• 3. Select the 'First Aid' tab on the top.

Solution 5: Reformat the unrecognized external SSD without data loss

If all solutions above don't work, the external SSD might be corrupted and you need to reformat it. Whether the external SSD is not recognized due to logical disk errors or hardware problems, the most important is your files on the drive.

The thing is, reformatting will cause data loss. So, to prevent data loss, you need to get your files off this external SSD first if you forget to back up. iBoysoft Data Recovery for Mac will help you get your data back within a few clicks.

After your important data is recovered, you can go ahead to fix this issue by reformatting without data loss.

Tutorial to reformat the unrecognized external SSD

This guide to reformat external SSD will remove all data on the external SSD, please make sure you have recovered all useful files with iBoysoft Data Recovery.

• 1. Launch Disk Utility.
• 2. Select the external SSD on the left part of the window.
• 3. Click 'Erase' on the top of the Disk Utility window.
• 4. Complete related information (name, format, scheme), then click Erase.

Solution 6: Send the external SSD to a local technician for help

If unfortunately, the external SSD can't show up in Disk Utility or the solutions above failed to fix external SSD not recognized issue, the drive might have some hardware problems. You need to contact the manufacturer for technical support or product replacement.

• Fix SSD not showing up in Windows 10/8/7

Why is external SSD not recognized on Mac?

Various reasons are leading to external SSD not showing up issue on Mac. Here we conclude four main causes as below:

1. The SATA to USB 3.0 adapter/Dock is malfunctioned.

Usually, you need to buy an additional dock, disk case, or SATA adapter to access an SSD drive. During this process, if the externally connected SSD is not recognized by your Mac, it's likely that the adapter is not compatible with the disk's SATA interface, or the dock/drive caddy is faulty.

2. The external SSD is new and uninitialized.

This happens when users externally connect the SSD to backup or transfer files on the internal hard drive. But many newly bought SSDs are not initialized with a file system, which means there is no entrance for macOS to recognize and communicate with this SSD, and for sure, the external SSD won't show up.

3. The external SSD has a file system that can't be recognized by Mac.

Possibly, the SSD that you try to access is formatted with a file system. However, it's not a file system that your Mac can recognize. For example, it is formatted with a Linux file system. In this case, your macOS can't recognize the external SSD surely.

4. New software or firmware needs to be updated.

This happens frequently for Samsung portable SSD T5/T3, because you need to install Samsung portable SSD Software to unlock disk's password and update certain firmware for this SSD. And if the necessary software and extension are not downloaded, you may receive 'No Samsung portable SSD is connected' from its software.

5. The external SSD is not set to show up on Mac.

Sometimes, your external SSD actually is recognized by the Mac, but some setups stop the SSD from showing up in the Finder, on the desktop, or even in the Disk Utility.

6. The external SSD is corrupted.

Another possible cause is that you have unsafely ejected your SSD, which makes the external drive corrupted after some core data like partition table or file system is damaged. Also, you need to be clear that the life span of an SSD is limited depending on how frequently you use it.

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7. Other Hardware problems.

Some SSD support pages you may need:

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• Samsung: https://www.samsung.com/semiconductor/minisite/ssd/support/warranty/
• Crucial: https://uk.crucial.com/gbr/en/support?cm_re=top-nav-v2-_-flyout-support-_-support-home
• Intel：https://supporttickets.intel.com/?lang=en-US
• WD: https://www.westerndigital.com/support
• Kingston: https://www.kingston.com/en/company/warranty
• Toshiba: https://www.toshiba-memory.com/warranty/