Big Sur - external discs not mount… | Apple Developer Forums

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Hi All,

I have a question. Just after the software upgrade from Catalina to Big Sur, my mac (Macbook Air 13-inch, Early 2015) stopped mounting any usb external discs. Doesn't matter, if it's an usb ssd card reader, usb stick, or external hdd. Does anyone have a similar problem, and any possible solution?

Thanks

macOS

70k

Posted by

JessieI

Reply

Solved ... for me at least ....Disk Utility -> First Aid

I had a very similar issue with my brand new Macbook Air M1 with BigSur 11.4

I have two Seagate 8TB drives, both formatted as eXFAT, which worked perfectly on my 2015 Macbook Pro Retina and an aged Dell M6800 running Windows 10.

No matter which drive, no matter how connected (Anker 6-in-1 PowerExpand usb-c hub. or another dongle usb-c to usb-3), I would ... a) not see the drive in Finder b) In Disk Utility the drive would be seen as not mounted, and would not mount manually c) powering up with the drive made no difference

Following an Apple Tip in this thread, I then ran First Aid on the drive using Disk Utility, but... FIRST: attempt a Disk Utility -> Mount, wait a while and close the error message that says can't mount .... important step. Then Run First Aid ...... a) select the show details tick box so you can see what's going on then proceed b) Accept any "can't mount" or "unmount" messages if they appear c) after very few minutes the drive was "repaired", mounted, visible in Finder, and all files & folders seemed intact. d) continued to work when drive disconnected & reconnected Most importantly, after the "repair" the drive still worked perfectly on my old Macbook & PC

I'll check out that the drive works with the other dongles and also do the same on my other 8TB drive.

I've just done that with the same results.

—
Billinski
I agree 100%. What is wrong with this company? They freely make changes that affects our data and hardware and then ignore us, the customers, with all the problems their changes create. And it's not; like they don't have the money to support their customers.

—
JudasPriest
Apple killed its desktop unit a few years ago. Alas. latest OS's show the loss.

—
henryec3

Replies

The solution provided by CAPYDAN works like a charm for me. I have an issue with Mac.

I did exactly the same, except that I select exFAT (instead of APFS) as I need to share data among MacOS, Windows and Linux as well.

Posted by

luuquanghung

i am facing this same problem. After i updated to Big Sur, no external drive is getting recognised, not even in the volumes section. Tried a usb stick (FAT32 format), WD external HD (macos journaled), both of them are not recognised on the OS
Please help me, have tried all the solutions mentioned in the above thread.
Currently on Big Sur 11.2.1, Macpro 2017

Posted by

pinkash_inferno

apple is not seeing the wood for the trees here. I had the exact problem. Checkboxed everything. Still no joy. Solution lies in this: mouseover sidebar where it says locations. When u mouseover, an expandable arrow appears (really dumb for it not to always be visible). Click on it and you will see your drives if they are visible say In disk utility.

Posted by

Stringfellow1

I have the same problem which came about on February 15th or so.
So far, I did not manage to solve the problem by using some of the suggestions posted above.
I have a MacBook Pro (Retina, 15-inch, Late 2013).
Processor 2 GHz Quad-Core Intel Core i7
Thanks for your help.

Posted by

AlbertoPettorossi

I have the same problem. I don't see CappyDan's instruction: Select the destination drive hardware (above the existing volume)

Posted by

Sealion

I also have this issue - in my case with a 2020 Macbook Air Core i7 (just pre m1)with 16GB and 1TB- I have 2 external SSDs hooked up via USB3 both of which are are formatted under APFS and used as Time Machine backup disks & supposed to alternate.

I had no issues until upgraded to Big Sur 11.2.2 48 hours ago...now neither volume mounts nor is even findable via Disk Utility (or any other method either).

I do not want to reformat and start again because of their use for restoring old document versions.

I ahem tried restarting and every other method I can think of. there is something afoot with the Big Sur External Disk recovnigitopn system...it needs a Bug Fix!!! Or at least that someone at Apple to acknowledge it exists!

Posted by

Markpf4

I have Big Sur OS with newest upgrade 11.2.2 and Mac Book Pro M1 2020 version. I'm using Thunderbolt 3 Dock Core and connecting external USB hard drives. They are mounted. Can be seen on Finder and there is an icon on pulpit. First aid done. Disc can be seen. Disc utility shows size of files own hard drive but is not showing the files itself. And it is for all external drives. :( On Microsoft Windows it works without any issues. Please help and do not say that I need to format a drive - it's just ****** and this is not a fix. :|

Posted by

Andrzej_Bil

I have a similar issue. I’m using an iMac (late 2014) and recently upgraded to Big Sur. For a while Big Sur displayed the external drives in Finder, but now they are gone. I have a Seagate 4 TB External drive with a photo library on it so I do not want to reformat the drive. The external drive shows up in the disk utility but cannot be mounted. My old MacBook Air can recognize and read/write the Seagate drive fine. Need help.

Posted by

Tprobe

Hi were u able to fix this? I have the same issue.

—
Ankush Mehta

So, I have a 16-inch MacBookPro that just started showing this problem. Big Sur 11.2.3 installed.

The USB drives (yes, now two of them) will no longer auto mount. However, their locations are showing in the /Volumes directory as if they are still mounted - only not really since they are (a) not connected and (b) the folder permissions are locked.

What is more interesting is that on a 15-inch MacBookPro Big Sur 11.2.3 these same exact USB drives mount correctly (as they always had). Both machines are very similarly configured as to software. Very minimal system software installed (iStats and LittleSnitch) plus the assortment of developer tools, browsers, and editors.

Also, I can mount these drives via the terminal (bash shell) via "sudo diskutil mount -mountPoint /path /dev/disk2s1"

In fact, I can even mount them onto the /Volumnes/diskname mount point (/Volumes/Andromeda) and have them work until I unmount them.

Even in Disk Utility, I can see the volumes but not mount them - even if they were mounted and I unmount them with Disk Utility and then try to mount them again. Complete failure with: "Could not mount “Andromeda”. (com.apple.DiskManagement.disenter error 49180.)"

I have rebooted, rebooted in safe mode, rebooted and reset the SMC, etc. I have also tried to remove the /Volumes/Andromeda mount point while the drive was not connected. Nothing lets me, even when booting into the recovery mode. Always claiming it is not permitted.

This seems like some corruption within the OS and it is somewhere written to disk such that it does not clear up and has not cleared up over the days I have been trying to recover from this.

Posted by

MichaelSinz

So, I have a 13-inch MacBookPro M1 that just started showing this problem. Big Sur 11.2.3 installed.

The USB flash drive will no longer auto mount. It loaded once, I could see the files, clicked on a file and the computer ejected the external drive. I cannot see any external drive, tried rebooting, disk utility without any success. The drive was created not long ago prior to Big Sur. I have critical files and think is related to what you all have posted. I cannot reformat drive. Need help, any other suggestions?

Posted by

DavidOGT

Hi, I am having the same problem. iMac pro upgrading to big sur, cannot find the external Sandisk extreme pro disk.

But I think there is a temporary way to mount the external disk.

go to disk utility
find your external disk, click and choose the disk
mount (top right corner of the utility window)
every time you mount the disk, you need to do 1-3

Hope this helps. Wish apple developers can solve this issue asap.

Posted by

haoyeah

I have bought a new MacBook Air in Feb 2021 - now all external drives refuse to be recognised and keep flashing - but will not mount - have tried all the solutions but to no avail - they all worked with my old MacBook Air - yes I am using Big Sur - but this has become a frustrating problem - not being able to access external data

Posted by

Amosgrouse

MacBook does not mount an external HD or a ScanDisk stick through its USB port

Disk Utility, hovering the sidebar and clicking 'Locations' as suggested in this post doesn't work
I can boot from the external HD fine (macOS 10.13.6) so I know the HD and the USB cable are fine
MacBook running Big Sur sees AirPort Time Capsule via WiFi
I can mount the external HD successfully attaching the HD to the AirPort's USB port

macOS Big Sur version 11.2.3
MacBook Air (13-inch, 2017)
Processor 1.8 GHz Dual-Core Intel Core i5

Posted by

grearte

Disturbing to see this question linger for months. I have the same issue with a new M1 MB Air. External Lacie Mobil USB-C drive, Time Machine can't use it. Finder can see it, but not any files on it.

Posted by

Steve_H

Same problem - and since my time machine backup is on an external drive, how can i even revert to an OS that works? Terrible experience with this “update” - not an update if it makes things you rely on useless, @apple.

Posted by

WageD