Pegasus2 R8 + Mac mini M4, drive disconnects repeatedly

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Mikko Malinen posted this 28 October 2025

Pegasus2 R8 + Mac mini M4 + Apple A1790 Thunderbolt 2 to 3 adapter: when Pegasus2 powers on, drives are mounted normally and I can access the data on the volumes. After waiting (or using the drives) for a while - usually 2-5 minutes - I get OS-level notifications there drives were unmounted abnormally. Similar issue has happened with both macOS Sequoia (initial OS that was installed on Mac mini M4) and macOS Tahoe.

Before Mac mini M4 I had Mac mini M1, and I was able to use Pegasus2 with the same adapter and cable without any issues for many years. I also have a Mac mini 2011, and Pegasus2 works perfectly without the adapter.

Promise Utility's Event log only shows "stopped by host unplug" as if the cable would have been disconnected, so it won't help much with debugging. macOS logs don't show any clear reason for ejection either.

Pegasus2 firmware is 5.04.0000.64 and I also have the latest DEXT driver installed on my Mac mini M4:

systemextensionsctl list | grep promise
com.promise.driverkit.pegasus (21.1.0/1) com.promise.driverkit.pegasus [activated enabled]

Any ideas what could be causing this behaviour or are you maybe having the same issue?

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Frank Bosma posted this 29 October 2025

Hi Mikko,

most likely cause is the thunderbolt adapter.
I had a similar case where customer had a spare adapter lying around which worked fine.

Kind regards,
Frank

Mikko Malinen posted this 3 weeks ago

Hi Frank,

I replaced by Thunderbolt 2 to 3 adapter, and this seems to have resolved the issue. Can't wrap my head around the fact that old adapter still works perfectly fine with Intel Mac mini 2011, but not with newer Apple Silicon Macs, but I'm of course happy that everything now works with new adapter.

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