Do not update to macOS 15.4 with Promise Pegasus

[BreuerEditor]

I just wanted to give a warning to pro users out there.

My brand new M4 Max Mac Studio just updated to macOS 15.4 overnight and now my Pegasus2 R8 isn't recognized and gave me all sorts of red lights and cycling issues. It was fine last night running 15.3. Even with the DEXT installed and confirming with tech support that the drivers are correctly installed, they had me put in for a support ticket. When plugged into M2 Pro MacBook Pro running macOS 15.3, there's no issue whatsoever so this is clearly a macOS 15.4 issue and not a cable/hardware issue.

UPDATE #1: I just got off the phone with AppleCare and she recommended I re-install macOS 15.4 from Recovery, but the odd thing is we tried a different port on the Mac Studio and it worked. If you're looking at the back, I was using the far left port and it was having cycling issues. When plugging into the 2nd from left port it's totally fine. Ironically, when plugging in a TB3 PCIe SSD into that far left port, it operates fine, but the Pegasus can't be located.

Hard to tell if it's a macOS compatibility issue or a combination of macOS and Mac Studio. I'll do a re-install of 15.4 on Friday and report back.

UPDATE #2: Promise did a screen-share session so they could run some tests. Everything looks normal.

UPDATE #3: Now the PCIe SSD that was plugged into the 2nd from far left port keeps disconnecting from the Mac Studio. I tried it in my CalDigit TB3 dock and it's doing the same thing. Something screwy is going on with the TB ports on the Mac Studio after upgrading to 15.4.

 

[mg974]

Hello,
This morning my Pegasus2 R8 stopped to mount on my Mac Studio M1 on sequoia 15.4.
I used this drive daily in the last weeks, no issue.

All the drives LED are blue but the power button LED of the unit is ORANGE.
I can't use promise utility because the app won't launch it's guy for unknown reason.
Did full uninstall / reinstall of software and hardware without solving the issue.

Contacted support and waiting for feedback.
Any idea is welcomed, thanks.

 

[BreuerEditor]

This is interesting that it's the same drive model, macOS version, and computer model but a different chip. I ended up returning my Mac Studio since I was within the 14-day period (as Apple suggested) and got another model that came as 15.3. Everything was fine, but I restored my 15.3 machine from a 15.4.1 Time Machine backup and began having additional issues with the mismatch in macOS versions. The AppleCare rep said I would be fine to upgrade to 15.4.1 and that it wouldn't affect the ports. I had the same issues as before but couldn't revert back to 15.3. After talking with Promise support and doing multiple tests, there is still no known solution. HOWEVER, try a different port on your Mac Studio. Chances are, it might work as it is for me. My Pegasus2 R8 is plugged into the far right port and it's working fine, but in any of the other ports, it's not recognized and shuts down. Just make sure you have the Promise DEXT Driver installed. If it doesn't notice it, uninstall it, restart your Mac Studio and reinstall the driver and that should work.

 

[mg974]

Hey, do

This is interesting that it's the same drive model, macOS version, and computer model but a different chip. I ended up returning my Mac Studio since I was within the 14-day period (as Apple suggested) and got another model that came as 15.3. Everything was fine, but I restored my 15.3 machine from a 15.4.1 Time Machine backup and began having additional issues with the mismatch in macOS versions. The AppleCare rep said I would be fine to upgrade to 15.4.1 and that it wouldn't affect the ports. I had the same issues as before but couldn't revert back to 15.3. After talking with Promise support and doing multiple tests, there is still no known solution. HOWEVER, try a different port on your Mac Studio. Chances are, it might work as it is for me. My Pegasus2 R8 is plugged into the far right port and it's working fine, but in any of the other ports, it's not recognized and shuts down. Just make sure you have the Promise DEXT Driver installed. If it doesn't notice it, uninstall it, restart your Mac Studio and reinstall the driver and that should work.

Hey thanks for all the additional infos.
In my case :
- DEXT driver reinstalled.
- port and cable changed.
- Full 10 min discharge of the unit without power and cables.
- Tried with my laptop M4 pro.
- Confirmed via terminal that the computer ports are working, can see the Pegasus R8 connected.
- In promiseutil terminal the utility doesn't see any subsystem.

It could be the RAID controller of the unit that doesn't boot correctly or is damaged.

 

[BreuerEditor]

Great info to know. Is your laptop M4 Pro capable of seeing the RAID? Is it running 15.4.x?

My M2 Pro 16" MacBook Pro is running 15.3 and doesn't have any issues with it, but there's no way I'm upgrading to 15.4.1 so I can have it as a backup system if my Mac Studio somehow doesn't work again with it.

 

[mg974]

Great info to know. Is your laptop M4 Pro capable of seeing the RAID? Is it running 15.4.x?

My M2 Pro 16" MacBook Pro is running 15.3 and doesn't have any issues with it, but there's no way I'm upgrading to 15.4.1 so I can have it as a backup system if my Mac Studio somehow doesn't work again with it.

Both computers are on 14.4.1
What's strange is that was already on the latest OS while working with the drive.
Davinci resolve crashed the computer, the pegasus didn't shut down, on reboot the computer wasn't seing it anymore.
After removing the pegasus power and plugin it back the power LED became orange.
Waiting for a quick connect with Seagate support.

I finished a project yesterday and was about to launch it today -_-

 

[BreuerEditor]

Got it. Hopefully you get some answers as I wait for Promise's tech support.