After I updated my Macbook Pro to Sequoia 15.5, my external hard drives will no longer mount via USB. Has anyone had this issue?
I've tried:
Restarting/unplugging, etc.
Plugging HD's into another computer, they work properly so the issue is not the HD or cable
Using Disk Utility to mount manually - the HD is listed in gray, the mount option is available but does nothing when clicked.
MacBook Pro 14″, macOS 15.5
Do you have another Mac to see if they are visible on it?
Do you have a separate volume with an older operating system that you can boot off of to see if the problem is the OS, or the drive?
Option key on boot lets you boot other boot volumes.
If the drives don't have their own source of power, it may be time to move them to a drive sleigh that does. The firmware on many external drive interfaces depend on a certain power level from the computer, and may need to be updated to be viewable on a newer OS.
USB and Thunderbolt both face issues with Energy Saver, and drives are best in their own external power supply (not supplied by the computer case) with the appropriate firmware for the OS:
USB/Thunderbolt & Energy Saver/Sleep/powe… - Apple Community
ExFAT and FAT32 are not Mac bootable.
NTFS is not Mac writable without extra software like NTFS MacFuse
Block sizes differ.
If you are going to share crossplatform data, read this tip:
How to format a drive, or disc for maximu… - Apple Community
Older drives use one of the following to diagnose more carefully:
In MacOS http://www.binaryfruit.com/ DriveDX
In Linux or Windows https://www.hdsentinel.com/
SMART errors indicate a drive is past its prime and probably ready to put to pasture.
Recovering data from Macs - Apple Community can help you recover items in Mac OS, although for really hard to read data, take it to a professional. If the data is worth thousands of dollars there is http://www.drivesavers.com/ If they can't recover it, no one can.
If the drive is readable, and just is slow mounting, make sure no volume is over 85% full.
My experience shows that mounting external drives does not happen immediately and it takes a while, about a few dozen seconds, but they mounts.
This has been a problem for me since I bought my m4 MacBook Pro a few months ago. At the moment, I have two types of drives that are giving me fits:
– Fat-32 formatted devices I need to store music files for a Raspberry Pi player (Moode) and that are connected to the Mac via sata-to-USB enclosures. Last time I updated a drive from my master disk, I had to use my old MacBook Air.
– 2 TB extFS formatted m.2 laptop memory stick that I use for another Pi player using an m.2 shield, where that is the required drive formatting. On my Pro, I have been attempting to connect it when installed in a pricey m.2-to-USB case by Sabrent. I formatted the drive with Paragon extFS for Mac, which worked just fine. Sometimes I can mount the drive on my Mac, sometimes not. It works just fine on the Pi player, so I don't think there's anything wrong with the SSD stick or the housing. It's not a cable problem.
I have tried both using the computer's USB ports directly and through a 100 watt+ hub that has always worked flawlessly before.
It is absolutely making me crazy and constantly causing problems. I've had Macs since 1986 and never had this problem.
have you even tried the solutions in these posts?
https://www.xda-developers.com/how-to-fix-an-external-drive-that-wont-mount-on-mac/
https://www.cisdem.com/resource/external-hard-drive-not-mounting-mac.html
good luck to you.
I selected the APFS format for the 2 external drives I use to connect to my Mac mini M4.
From experience with external drives you need to be so careful when selected the best and correct file format to be read by your operating system, because there is nothing so scary when your computer can't / won't access that ext hdd.
Personally myself I would never use the Fat32 file format for any ext hdd's to connect to any of the newer Apple computers.
External hard drives not mounting after Sequoia 15.5 update
