MP 1,1-5,1 OCLP Monterey shutdown issue

[sirroderick]

I now have Monterey running successfully on one of my Mac Pros. I'm absolutely delighted with the performance but I have one rather annoying issue. If the machine has been been on for more than a few hours it won't shutdown. Initially it seems to shutdown as normal but then instantly reboots (without intervention). Successive shutdowns result in the same behaviour and a hard reset then becomes the only way to shutdown. I don't think I've ever seen this on a Mac before.

 

[paalb]

I now have Monterey running successfully on one of my Mac Pros. I'm absolutely delighted with the performance but I have one rather annoying issue. If the machine has been been on for more than a few hours it won't shutdown. Initially it seems to shutdown as normal but then instantly reboots (without intervention). Successive shutdowns result in the same behaviour and a hard reset then becomes the only way to shutdown. I don't think I've ever seen this on a Mac before.

Not me either. I wonder what happens if you use the terminal with sudo shutdown -h now ?

 

[sirroderick]

Not me either. I wonder what happens if you use the terminal with sudo shutdown -h now ?

I'll give that a try next time it happens. Thanks.

 

[paalb]

I'll give that a try next time it happens. Thanks.

I have heard that a low battery can give you a lot of strange behaviours.

 

[sirroderick]

Pretty sure I replaced the battery some years ago also quite a coincidence it starts a few days after the Monterey OCLP install. It's only happened 3 times so far but I don't like having to switch the mains off. Instinctively it doesn't feel like it's very good for the machine. If the terminal command works then I can live with it.

 

[zterm]

I have had that issue with one of my 5,1 before, not with Monterey but with Mojave.
What solved my particular problem back then:

Do a hard shut down.
Disconnect all the USB devices including the keyboard.
Restart the computer.
Once the computer started, connect a wired USB keyboard and try to shut down the computer.
If it fails, do a hard shut down.
Turn on the computer again and do a PRAM reset.
Once the computer started, hopefully it will shut down normally and you can re-connect USB devices.

 

[sirroderick]

Interesting. Will def give that a try. Hasn't happened for a couple of days now but I'm sure it'll come back sooner or later. Thanks.

 

[sirroderick]

I'll give that a try next time it happens. Thanks.

It just happened again and I tried sudo shutdown -h now as you suggested and that does exactly the same (i.e. restart instead of shutdown).