SSD ejecting while transferring files?
using a new WD 1TB SSD from sandisk, M.2 NVMe,
its inside a PULWTOP USB-C Dock for iMac 24 inch hub,
it keeps ejecting when transferring 2GB+ size files,
booting into safe mode stops this happening but i shouldn't have to keep doing that obviously,
all drives are APFS
iMac is M4
Why is it happening and how can i stop it happening?
Short answer:
The drive is being force-ejected because the dock can’t keep it powered and stable under heavy I/O. A better enclosure or a powered hub will stop the ejects permanently.
A bit longer answer:
I believe what you’re seeing is almost always a power, firmware, or USB controller issue, not a problem with APFS or macOS itself. Your WD/SanDisk is likely fine, but the PULWTOP USB-C dock can’t reliably sustain the power and data load when large transfers hit peak throughput. In Safe Mode, macOS disables third-party extensions and background services, which lowers USB bus stress—so the drive stays mounted. That’s why the symptom disappears there.
The fix is usually straightforward once you target the real cause. Start with these steps, in order:
If the issue persists, the dock is the bottleneck—I suggest replacing it with a powered Thunderbolt or USB-C hub that can deliver stable current.
Short answer:
The drive is being force-ejected because the dock can’t keep it powered and stable under heavy I/O. A better enclosure or a powered hub will stop the ejects permanently.
A bit longer answer:
I believe what you’re seeing is almost always a power, firmware, or USB controller issue, not a problem with APFS or macOS itself. Your WD/SanDisk is likely fine, but the PULWTOP USB-C dock can’t reliably sustain the power and data load when large transfers hit peak throughput. In Safe Mode, macOS disables third-party extensions and background services, which lowers USB bus stress—so the drive stays mounted. That’s why the symptom disappears there.
The fix is usually straightforward once you target the real cause. Start with these steps, in order:
If the issue persists, the dock is the bottleneck—I suggest replacing it with a powered Thunderbolt or USB-C hub that can deliver stable current.
I concur 100% with Tesserax.
I would first try disconnecting the other USB devices from the Dock to see if that helps.
If not, then return that Dock (if you still can) and buy a drive enclosure for the WD NVMe drive. Then buy a self- powered hub or dock for your additional USB devices.
If you look for self powered docs check out OWC (MacSales.com). They are considered by most of the experienced users here to be the premier hardware supplier for Macs. Call their customer support to have them suggest which of the several docks they have meet your hardware, workflow and budget requirements.
Another possibility is the SSD is overheating which can happen on large transfers since you specifically mention an M.2 NVMe SSD. This can happen if the SSD is installed into a device with insufficient cooling and airflow.
there is no option to “Put hard disks to sleep when possible.” In System Settings → Energy,
using latest Tahoe
usb-c cable is short but hardwired to dock
WD/Sandisk doesn't support Macs for their Dashboard tool
thank you for the detailed explanation, it makes perfect sense, will look into a powered dock if it gets too annoying
can't find anything there that meets my requirements,
must have SD card slot,
must hold my current M.2 SSD,
must not cost silly money
SSD ejecting while transferring files
