iMac Kernel panic on shutdown/restart

[CooperBox]

Normally I never shut down my 2020 iMac but at the end of each day put it into sleep mode with never a problem.
The last few days however to be a little more ECO friendly I've been shutting it down. The screen goes black for a minute or two and appears to have shut down, then it auto starts with a very brief typical kernel panic message, then the Apple logo appearing ok and then the login screen. Just before login I get a prompt similar to 'Computer failed to shut down, send message to Apple Yes/No. It boots ok on selecting No, otherwise gives the kernel panic codes shown below.
It's an iMac 20,1 3,3GHz A5 with AMD Radeon 5300 4GB and 64GB Crucial RAM (4x16 equally paired). Running Big Sur 11.7.7.
The iMac performs wonderfully otherwise, so I hope this appears to be just an annoying minor hiccup.
Can anyone here who loves deciphering these funky messages throw any light on what's happening here?

 

[Insidious]

Not a solution to the issue, but why not update to 11.7.9?

 

[BrianBaughn]

If you have anything attached to the iMac have you tried with it all disconnected?

 

[MacMike81]

I cannot decipher the cryptic error reports, but I just went through a long battle of “your system was restarted because of an error” everytime I would wake from sleep.

I just recently replaced the Fusion Drive with a SSD in hopes to correct the problem. It doesn’t take much searching on this forum to see that apparently these Fusions Drives are hitting End of Life all at once! Lol. I suggest doing a backup ASAP and consider changing the drive.

 

[CooperBox]

I cannot decipher the cryptic error reports, but I just went through a long battle of “your system was restarted because of an error” everytime I would wake from sleep.

I just recently replaced the Fusion Drive with a SSD in hopes to correct the problem. It doesn’t take much searching on this forum to see that apparently these Fusions Drives are hitting End of Life all at once! Lol. I suggest doing a backup ASAP and consider changing the drive.

I appreciate the reply. The 2020 iMac20,1 however doesn't have a fusion drive, which was one reason for going for that over the 2019 model. For info, yes I have a cloned backup of the iMac's system.

 

[CooperBox]

If you have anything attached to the iMac have you tried with it all disconnected?

Interestingly enough this is exactly what I tried the day after posting my query, as I have 2 external SSD's permanently connected.
Disconnecting them both from the Finder prior to shut down solved the problem, and I've not seen a kernal panic since.

 

[Big Apple Tim]

I can't believe iMacs are still doing this. Saw random kernel panics or 'Unexpected Shutdown' as Apple called it on every iMac using the 2012 skinny design and still happening now. Advice to AASP used to be to replace the PSU and the MLB as one would damage the other...

 

[CooperBox]

I can't believe iMacs are still doing this. Saw random kernel panics or 'Unexpected Shutdown' as Apple called it on every iMac using the 2012 skinny design and still happening now. Advice to AASP used to be to replace the PSU and the MLB as one would damage the other...

Just for info, in addition to my 2020 iMac, I used a 2010 27" iMac until last year then donated it to a family member. Never saw a kernel panic on it or any other significant problem, and with an SSD I installed it's still running faultlessly with 10.13.6 High Sierra. Also have a 2009 27" iMac which I repaired and used quite extensively, still performs well with no kernal panics under my ownership. Have no experience though with early 'skinny' design iMacs.

 

[BrianBaughn]

I would try with each SSD connected on its own…to determine which one is causing the panics if indeed one is the cause.

If you do figure out it's a particular one and they're the same sort of SSD you could swap out cables/housings to narrow things down even more.

 

[bergert]

I have the same issue on MacStudio M1 (12.7); since 12.6.3 the panic log is empty. I have an external TB3-RAID enclusure (ARC-8050T3) connected, with a SAS-SSD and other RAID volumes. The panic happens 2 out of 3 times on shutdown: sometimes, I can shutdown without panic. The only way to avoid is unmount the disks and disconnect the USB-c (TB) cable. I was using the same hardware with the same SSD on MacPro (2013) with the Apple TB->USB-c dongle without issues for 2 years before the Studio. Never had a panic with BigSur. The shutdown will panic/restart - and then shutdown/panic/restart over and over ... (several times in a row) - until I disconnect the TB cable. The shutdown panic hangs the computer - until several minutes later, it restarts and the logon screen appears. Apple is not looking at the crash dumps we submit?

Edit: It's me the user requesting the shutdown - then the panic/restart happens, and user is selecting ShutDown again, this time from the logon screen (and again shutdown+panic).

 

[bergert]

update: I managed to get a reply from tech support, and they fixed it with the 14.4.1 update. Using an external enclosure with driver, in the diagnostic dump the SAS-SSD is shown as "solid state disk: yes".

I have only performed 4 shutdowns so far - but there is no more panic. This is the error (OS 14.4):
panic(cpu 1 caller 0xfffffe0014da1168): Halt/Restart Timed Out @IOPlatformExpert.cpp:884

 

[MacMike81]

update: I managed to get a reply from tech support, and they fixed it with the 14.4.1 update. Using an external enclosure with driver, in the diagnostic dump the SAS-SSD is shown as "solid state disk: yes".

I have only performed 4 shutdowns so far - but there is no more panic. This is the error (OS 14.4):
panic(cpu 1 caller 0xfffffe0014da1168): Halt/Restart Timed Out @IOPlatformExpert.cpp:884

That’s awesome!

I went to Monterey 12.7.4 and I haven’t gotten any kernel panics in a while