An external hard drive is useful if you want to store large files from your Mac. If you use an external hard drive you can store a lot more data, especially if your Mac is limited by the built-in hard drive.
An external hard drive also helps if you want to take data from your Mac to another location or use it on multiple Mac computers. If you regularly encounter the message that your is out of disk space on your Mac then it is also advisable to move data to the external hard drive. Your Mac becomes significantly faster by moving data to a fast (SSD) hard drive because you are running low on disk space your Mac is slowing down.
However, it also happens that the hard drive is not recognized by macOS. This may be due to incorrectly disconnecting your hard drive. If you do not remove the hard drive properly first, the external drive may no longer be recognized after reconnection.
Mac not detecting hard drive
Turn off Mac and disconnect external hard drive
If the external hard drive has always worked and was visible in Finder. Then it may help to turn off the Mac (do not restart) and disconnect all USB devices connected to the Mac. Then wait 5 minutes, switch on the Mac again and, once the Mac has completely restarted, reconnect all USB devices.
This way, the Mac will reconnect to the connected USB devices and the external hard drive may be found.
Check external hard drive cables
To avoid connection problems, check all cables to and from the external hard drive and your Mac. Consider the power cable to the socket, the USB cable(s), etc. Always use the official cables to connect, no alternative/counterfeit cables and no USB hubs (a USB cable with multiple USB inputs). Using alternative cables may cause a connection problem between your Mac and the external hard drive, which may prevent your Mac from finding the external hard drive.
Hard drive shortcut not visible
To start, let's check whether the hard drive is visible in Finder. It happens that the hard drive is connected in macOS but is not visible.
Open Finder. Go to Finder at the top of the menu and then Preferences. Go to the General tab and check whether the options: Hard drives and External drives are checked.
The shortcuts to the drives are displayed on it MacOS Desktop. If you don't see the shortcuts, continue to the next step.
Disk Utility
You can use the Disk Utility to detect and fix external hard drive problems.
Press the Command ⌘ + Spacebar keys on your keyboard. In Spotlight type: Disk Utility. Launch Disk Utility. In the left menu select your external hard drive and then click on Disk First Aid.
Check for any problems and resolve them by following the instructions. If you cannot find the drive or there are still problems, continue to the next step.
Format the external hard drive
If you see your hard drive in Disk Utility but can't open it on your Mac, you may have a problem with the drive layout.
In this case, you will need to reformat the drive. PCs with Windows operating systems use the New Technology File System (NTFS). Mac computers running macOS operating systems, on the other hand, use the Hierarchical File System (HFS+).
By default, USB sticks and other external drives are formatted with the NTFS file system. This works great on PCs, while Macs can read data in the format but struggle to write it. Fortunately, you can format your external drive with the File Allocation Table (FAT32) or Extended File Allocation Table (ExFAT) file system.
Format FAT32 is fully compatible with all versions of Windows and Mac operating systems. Unfortunately, this particular file system does have file size limitations. The maximum size of supported files is 4GB, which means you cannot write files larger than 4GB. Nor can you startup disk for Macs within storage media that use the FAT32 file system.
Suppose you don't plan to use external storage to transfer large files or create executable partitions. In that case, the FAT32 format can be a good option.
ExFAT is a file system format that has an advantage over the FAT32 file system. It has no limitations on file or partition size. Therefore, you can write a file with a size of 1TB and create 5TB partitions within the device. Despite the improved data size, some older versions of the MacOS operating systems are no longer compatible with this file system format.
If you haven't started Disk Utility yet.
Press the Command ⌘ + Spacebar keys on your keyboard. In Spotlight type: Disk Utility. Launch Disk Utility. In the left menu select your external hard drive and then click Erase.
Select the desired structure, exFAT, macOS extended (journaled) or MS-DOS (FAT) and click Erase. I guessed ExFAT structure at.
Please note, all data on the external hard drive will be deleted!
Still not recognized? Or do you not want to erase the data? Then continue to the next step to diagnose the external drive problem.
Sideboard
Press the Command ⌘ + Spacebar keys on your keyboard. In Spotlight type: Console. Open the Console utility.
Disconnect your external hard drive from your Mac. In the left menu select your device (your Mac). Click the button, start streaming.
Now connect the external hard drive to your Mac. If error messages appear in the console, review them and find a solution. You can also post the error message in the comment field below with your request for help. I'm going to try to help you.
Solve Mac problems with CleanMyMac
I hope this helped you. Thank you for reading!
View comments (118)
Thanks for the quick reply.
But...unfortunately, I did both suggestions, but neither my iMac (after restarting) nor a Windows computer sees that new SeaGate Expansion HDD!
Do you have any other suggestions?
Hello, please make sure the data and power cables are properly connected to the hard drive and your computer. If possible, try other cables to rule out a defective cable. Do you hear the HDD spinning? Then take the HDD to a computer shop for examination.
Success!
thanks!
I have a new external HDD (HDD) from SeaGate (Expansion; 2TB). I want to use it for backups of my iMac (from December 2012) that runs OS 15.3 (Catalina). The HD can be used according to the specifications for both PC and Mac, but before using TimeMachine to make backups the drive must be reformatted. It did not say which structure; on the internet I found that it is best to go to "Mac OS extended (journaled)". So acted. Selected the external HD via the disk utility, erased it and formatted it to Mac OS extended. Result: "formatting failed"!! Then my computer could no longer see the drive either. When I connected I got the message "Disk cannot be read on this computer". (which was originally possible).
> can that drive still be salvaged? Or has it become permanently unusable? If salvation is still possible: how?
I am very curious about your response.
Hello, disconnect the USB and restart your Mac first. After restarting, connect the external HD and check via disk utility whether you can now see the disk. Otherwise, connect the drive to a Windows computer and check if you see the drive there via Disk Management. In Windows, if the drive is visible there, format it as exfat. Good luck!
Hi Stephen,
My external hard drive suddenly stopped working.
When I do 'Disc First Aid'; then I get the message: 'Performing the Disk First Aid failed. if possible, back up this volume".
I can't reactivate it either.
I don't want to delete it, because it contains all the files I need. In addition, I currently no longer have a Windows computer at my disposal.
What options do I have left?
Hello, here are some options:
https://www.macfreak.nl/hardware-macintosh/ssd-niet-te-herstellen/In any case, I would connect the drive to a Windows computer at a friend's house to see if the data can be removed this way. The message above states that the SSD may be breaking down, and various tools are recommended to check this. Try that.
Success!
Hi Stefan, I recently purchased a Macbook air M1. Previously I had a Macbook Pro and my hard drive worked fine on it. Now I see it in disk utility, but I can't activate it. In the console I get the following messages:
CoreData: Unable to create token NSXPCConnection. NSXPCStoreServerEndpointFactory 0x1458122c0 -newEndpoint returned nil
error: Failed to create NSXPCConnection
1 duplicate report for Sandbox: Family(1043) deny(1) mach-lookup com.apple.contactsd.persistence
Sandbox: Google Chrome Helper (GPU)(782) deny(1) mach-lookup com.apple.audio.audiohald
No idea if everything is relevant, but I've already tested everything else. I think I had an NTFS for mac program on the old one, but it is not on the new one (and I no longer remember the login). I would really like to know if you can help me.
Greetings,
Eva
Hi,
Indeed, you need NTFS for Mac to read and edit NTFS formatted external drive. You can download this program here and purchase it if necessary:
https://www.paragon-software.com/home/ntfs-mac/Video for more information:
https://www.youtube.com/watch?v=0EXmDmHm6egAfter this you should be able to read the data from the external hard drive. Good luck!
Thank you Stefan. I can now access my files again. Thanks for your quick response!
I have a new SSD external drive. On a Windows PC it is recognized and works fine. On my Mac, I don't see the drive in Finder. The disk can be seen in Disk Utility. However, the disk is not mounted. When I mount the drive I get the following error message:
"Activating "Disk" failed. (com.apple.DiskNanagement.disenter error 53249)"
How can I solve this?
Hello, you can solve this in the following way:
Try restarting your Mac first, doesn't that work? Then try the following:
Connect the drive to a Windows PC/laptop.
Open "This PC", right-click on the HDD/SSD you want to scan and choose "Properties".
Under the "Tools" tab, click the "Check" button under the Error Checking section.
You can then choose to scan the drive or repair it if any errors are found.
After repairing, the drive will also be repaired for Mac.
Success!
Thanks in advance
For several days now, the backup I make with Timemachine could no longer be written off. Today my external hard drive can no longer be accessed by my Mac. I have performed your help procedures, but do not want to erase the disk because it contains my ITunes files... I do not want to lose them. I have received the following error messages when using the Console program:
[Request 0x7fd502e79ee0] Finishing request with error 0x7fd502d63dd0
[ERROR] - Unknown CGXDisplayDevice: 0x41dc9d00
It doesn't say how to solve this problem.
Today I received a new hard drive. Both are LaCie d2 external drives.
Can you help me?
Many thanks in advance,
Liesbth De Groodt
Hello, isn't the external hard drive just full of backups? Unfortunately I can't do anything with the error message. Also restart your Mac. Unfortunately I have no additional information.
Dear Stephen,
Yes, I see in the data of the disk that it is full. I don't really understand that, because when I was still able to view the drive, I put about 150 backups (2010,2011, 2012 and XNUMX) of the external drive into the Mac's trash and emptied them. Also a number of large photo files, which I also have on the Mac. I then noticed that the disk still remained full for a while. I didn't understand that. From your answers to other people seeking help, I understand that a Window PC can sometimes still read the disk. I wanted to go to a friend's house to try that and transfer the files I absolutely wanted to keep. Is that a good idea? Do you have any other suggestions?
vgr
Liesbeth
Hello, maybe there are hidden files on the external hard drive filling up the drive.
https://www.pc-tips.info/tips/mac-osx/verborgen-bestanden-weergeven-mac-finder/
I have no additional tips if the disk is indeed full, remove files as you indicate.
Success!
Thank you.. But I don't know if it will be a solution for my ext. LaCie HD :-(
default 14:59:44.641894+0200 kernel LQM-WIFI: TX(FF:FF:FF:FF:FF:FF) AC VI (5001ms)
default 14:59:44.641905+0200 kernel LQM-WIFI: TX(FF:FF:FF:FF:FF:FF) AC VO (5001ms)
standard 14:59:44.920022+0200 bluetoothd Classic [0xc]: time 111, coex 0, rssi -47, tx [S= 0:F= 0], rx [S= 89:F= 0], Pkt Tx{0 0 0}{0 0 0}{0 0 0} Rx{89 0 0}{0 0 0}{0 0 0}
standard 14:59:44.920298+0200 bluetoothd Current NF value -97, current USB detected 3
default 14:59:45.064260+0200 nearbyd #ses-devicepresence,Ignoring weak RSSI -63.000000 on channel 39 for device: (device hash: 0x7209717) because we cannot trust weak RSSI due to a BT FW bug
default 14:59:45.069447+0200 locationd {"msg":"onAvengerAdvertisementDetected: got avenger advertisement", "subHarvester":"Avenger"}
default 14:59:45.069500+0200 locationd {"msg":"convertToSPAdvertisement", "address":, "data":, "date":, "rssi":, "status":, "reserved":, "subHarvester ":"Avenger"}
default 14:59:45.069535+0200 locationd {"msg":"onAvengerAdvertisementDetected: advertisment is near-owned from other people and do not process it", "subHarvester":"Avenger"}
default 14:59:45.069710+0200 locationd saveBeaconPayload: 1
default 14:59:45.070899+0200 nearbyd #ses-devicepresence,Ignoring weak RSSI -78.000000 on channel 39 for device: (device hash: 0x6df89e5) because we cannot trust weak RSSI due to a BT FW bug
standard 14:59:45.070837+0200 searchpartyd Publishing 1 advertisements to subscribers.
default 14:59:45.141120+0200 heard -[AXHeardController shutdownIfPossible]:337 BT not yet ready, delaying shutdown check
default 14:59:45.227006+0200 kernel memorystatus_update(enter): pid 4708, priority 210, dirty=0x0, Active(-1MB NF), Inactive(-1MB, NF)
default 14:59:45.227041+0200 kernel memorystatus_update: init: limit on pid 4708 (-1MB F ) targeting priority(210) dirty?=0x0
default 14:59:45.239290+0200 kernel memorystatus_update(enter): pid 4708, priority 40, dirty=0x0, Active(50MB NF), Inactive(50MB, NF)
default 14:59:45.239319+0200 kernel memorystatus_update: init: limit on pid 4708 (50MB NF) targeting priority(40) dirty?=0x0
default 14:59:45.285995+0200 AppleCamera Assistant Launching
Hello, does the LaCie external hard drive show up in Disk Management? If so, format the drive to ExFAT. Good luck!
Hi Stephen,
I have a My Passport hard drive that I have been using on my macbook for years. Suddenly my MacBook no longer recognized the hard drive. I went through the steps in your article. When I connect the hard drive I hear it turning on (the drive has a blowing sound) but it is not displayed on my desktop and/or in finder. I can see the hard drive in the disk utility but I don't want to format it because I don't have a copy of the data so I can't erase the drive as this data is important to me.
While adding in the console, I see a lot of messages, but I don't understand how to recognize error messages... I'm none the wiser. What is your advice?
Regards,
Amber
and oh yes, the hard drive is also connected to a Windows device (laptop). Here too I hear the hard drive 'turning on' but it is not recognized by explorer.
Hello, here you can read some additional tips in English.
https://apple.stackexchange.com/questions/149067/external-hdd-can-be-seen-in-disk-utility-but-not-in-finderSuccess!Hi Stefan,
Thanks for your article, but unfortunately I couldn't find a solution for the following. Hopefully you can help me with this. I have a fairly old hard drive that doesn't show up on my MacBook, not even in Disk Utility or Consule. The hard drive has also not been used for 5+ years. I also connected it to another MacBook, but it doesn't find it there either. Unfortunately I don't have Windows nearby.
Do you perhaps know a solution?
Thank you very much in advance!
Regards,
Lenna
Hi, just connect it to a Windows PC anyway. In addition, use original cables, replace the cables if necessary - USB I suspect.
Because it's a hard drive, not an SSD? Listen for the HD. If it literally runs and therefore works, you may be able to have the data read by a specialist if it concerns important data. If the HD is not found on two Macs, only Windows is an option, or Linux. Unfortunately, the options are limited. Hopefully it will be of some use to you. Good luck!
Hey Hello Stefan,
Hopefully you can help me with the following problem; My external hard drive recently "unsafely removed" itself and can no longer be found by my Mac. Still available in disk utility, but deactivated. And activation is no longer possible, nor is disk first aid.
I then connected it to a Windows laptop, where the PC had a lot of difficulty reading the disk and after a long wait and crashes, my files appeared there.
I then tried to run "Troubleshooter" over the disk, which normally finishes within an hour. This now costs a day. Transferring files didn't work at all either, considering it's a 5TB drive. And he really has a lot of trouble loading everything.
I then connected it back to the mac, along with another drive. I have the files restored to that properly functioning disk (via disk utility). It has been working on this alone for almost 21 hours, with still the same message that it is running. And the loading bar that slides back and forth.
I have a hard feeling that this will work, but before I disconnect it I was wondering if you have a solution? Unfortunately I don't learn anything from console.
Thank you very much in advance!
Greetings,
Shane
Okay hahaha I see he posted the message after all. nvm!