If you’ve been following along with the upgrade saga of Mr. Jackpot, I’ve got good and bad news to report. The good news is that I think I’m finally back on track now, but the bad news is that I basically need to start all over from scratch. When we last left the story, I had the fan cable problem resolved and was busy clean installing all of my apps and re-building the Music library. This was progressing nicely – I had made my first pass through all of the old music files, adding only songs and albums I wanted to keep, along with finding or updating album artwork for every file. That was about as far as I made it before we went out of town for a few days. When I came back home, the iMac was on with the dreaded flashing question mark folder.

It didn’t seem like we had experienced a power outage, so I first tried a hard restart. The Apple logo appeared and the progress bar started across, but just before it reached the end, the screen went black and the iMac appeared to shut off. I connected the external clone drive I made of the original internal SSD and rebooted again holding down the option key. This brought up the screen that allows you to select which drive you want to boot from, so I selected the clone and hit enter. That made it through to the user login screen, followed by the multi-language kernel panic message. After that went away, the panic log window appeared:

panic(cpu 0 caller 0xffffff7f8e24b231): nvme: “Fatal error occurred. CSTS=0x1 US[1]=0x0 US[0]=0xb VID=0x126f DID=0x2262
. FW Revision=42A0S63A\n”@/AppleInternal/BuildRoot/Library/Caches/com.apple.xbs/Sources/IONVMeFamily/
IONVMeFamily-470.100.17/IONVMeController.cpp:5320
Backtrace (CPU 0), Frame : Return Address
0xffffff83cb2c39e0 : 0xffffff800c51f5cd
0xffffff83cb2c3a30 : 0xffffff800c658b05
0xffffff83cb2c3a70 : 0xffffff800c64a68e
0xffffff83cb2c3ac0 : 0xffffff800c4c5a40
0xffffff83cb2c3ae0 : 0xffffff800c51ec97
0xffffff83cb2c3be0 : 0xffffff800c51f087
0xffffff83cb2c3c30 : 0xffffff800ccc27ec
0xffffff83cb2c3ca0 : 0xffffff7f8e24b231
0xffffff83cb2c3cc0 : 0xffffff7f8e236362
0xffffff83cb2c3e20 : 0xffffff800cc33409
0xffffff83cb2c3e90 : 0xffffff800cc33329
0xffffff83cb2c3ec0 : 0xffffff800c561565
0xffffff83cb2c3f40 : 0xffffff800c561091
0xffffff83cb2c3fa0 : 0xffffff800c4c513e
Kernel Extensions in backtrace:
com.apple.iokit.IONVMeFamily(2.1)[1898DCFE-5C18-3D87-B9E7-DFC0D22FD7EE]@0xffffff7f8e228000->0xffffff7f8e26afff
dependency: com.apple.driver.AppleMobileFileIntegrity(1.0.5)[0425E074-601A-3487-A54F-1E675D065186]@0xffffff7f8cf87000
dependency: com.apple.iokit.IOPCIFamily(2.9)[3C56BB73-D149-3E84-A2EB-DF806779B96C]@0xffffff7f8d101000
dependency: com.apple.driver.AppleEFINVRAM(2.1)[4E64E519-CD9C-3D03-8E62-1074E9AD54A7]@0xffffff7f8d309000
dependency: com.apple.iokit.IOStorageFamily(2.1)[E13E9C61-F1F5-3A81-B1EF-65669C3CBDBF]@0xffffff7f8ce65000
dependency: com.apple.iokit.IOReportFamily(47)[1FB49168-0280-3F04-A99A-F830C915E994]@0xffffff7f8d02f000

BSD process name corresponding to current thread: kernel_task

Mac OS version:
19F96

Kernel version:
Darwin Kernel Version 19.5.0: Thu Apr 30 18:25:59 PDT 2020; root:xnu-6153.121.1~7/RELEASE_X86_64
Kernel UUID: 7B7F06EE-1B75-345E-B898-2FD4FEC20F0D
Kernel slide: 0x000000000c200000
Kernel text base: 0xffffff800c400000
__HIB text base: 0xffffff800c300000
System model name: iMac18,2 (Mac-77F17D7DA9285301)
System shutdown begun: NO
Panic diags file available: YES (0x0)

This wasn’t super helpful while Googling, but I thought I could at least stay booted to the clone. Unfortunately, when I tried to launch Disk Utility and check the new internal SSD, the screen went black again and the iMac shut down. I tried this process several times and every single time it would eventually shut down. My initial thought was that the new RAM was bad, since it was happening on both internal and external drives and I had that happen once before when I worked at Northwest Airlines.

I sent Other World Computing a support request and went back to work using my phone and laptop. OWC didn’t reply to my initial support request, so a few days later I started an online support chat with them to ask about the status of my ticket. Even that took a few hours before someone popped up, but eventually a tech suggested I get a wired keyboard and try to 1) reset the PRAM and 2) boot into diagnostic mode.

Since I didn’t want to buy a new keyboard, I rode into work and borrowed an extra Windows keyboard. The PRAM reset (option-command-P-R) didn’t make any difference, but I was able to boot into diagnostic mode (hold the “D” key while starting up). It ran tests for about five minutes, but then came back with “No issues found. Reference Code: ADP000.” I left the machine up for about 30 minutes in that mode and it never kernel panicked. I tried to reset the SMC by unplugging the power for 15 seconds, then plugging it back in, but that made no difference. Lastly, I tried to boot into recovery mode (option-R) and was able to get as far as launching Disk Utility before it crashed. I did recovery mode one more time in an effort to launch the Catalina installer, but that also ended in a crash midway through installation.

I then talked to Armon (who was an Apple Genius when I hired him) and he said to try booting into verbose mode, then single user mode. When I did verbose mode (option-V), all of the usual junk appeared on the screen, then it switched back to the white Apple logo with the progress bar. It did finish all the way across, then launched a Catalina install screen (!?). That stayed up for about two minutes before crashing and shutting down. I got to the command prompt in single user mode (option-S), but when I tried to mount the drive (/sbin/mount -uw /), it kept displaying “disk2s1: device is write locked.” I then tried to use internet recovery mode (shift-option-command-R), which connected successfully to my WiFi network and loaded a disk image into memory without crashing. I started Disk Utility to reformat the internal SSD, but it did not appear in the window of available drives. Commands in Terminal couldn’t see it either. Huh.

At this point, I asked OWC support via email if this model could really support 32GB of RAM, as some online sites listed 16GB as the maximum. They told me that it could actually support up to 64GB of RAM and that they were highly suspect of the RAM being bad. I told him that I was going to open it back up and reinstall the stock RAM, then see what happened. I really didn’t want to go through that whole process again, but I really didn’t have any other option (aside from taking it somewhere like The Foundation). I spent an hour or so doing the surgery, then tried to boot up from the internal drive. Fingers crossed, but startup ended with yet another kernel panic. ARGH!

I did the surgery *again* and reinstalled both the new RAM and the old internal SSD. Fired it back up and it’s been running without a kernel panic for two days now. I emailed OWC and told them I needed to RMA the new SSD and I’m still waiting for a reply. I know they have a COVID note on their support page (“we are seeing increased levels of engagement across all of our customer contact systems”), but it’s been a bit disappointing to go through this experience. At least I’m getting very familiar with the inside of this particular model. Which, of course, means that there will definitely be an extra cool new iMac announced at WWDC…