Kernel Panic report, Imac late 2015

My Mac recently started restarting during video calls, and then things got worse and it now restarts very often. I installed Big Sur as my mac is a late 2015 27 inch imac, intel, and I read somewhere that newer OS's might be the issue?


So everything was wiped and I have a clean install of Big sur 11.7.8 and still the issue persists.


I have added the error report and have no idea how to decipher it, any ideas?


iMac 27″, macOS 11.0

Posted on Jul 6, 2023 10:20 AM

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15 replies

Jul 6, 2023 12:48 PM in response to kirsteeee

Most likely this is a hardware error so make sure to disconnect all external devices in case one of them is causing a problem. There is a slight chance some third party software could be causing it, so run EtreCheck and post the report here so we can review it for clues.


You may also want to run the Apple Diagnostics to see if any hardware issues are detected.


Jul 12, 2023 7:38 AM in response to HWTech

HWTech wrote:

But running macOS with just 4GB of RAM will be extremely limiting, but Ok for just the most basic of tasks.


I take it that this 27" iMac had 8 GB (2 x 4 GB), and now has only 4 GB (1 x 4 GB). So there three open slots. You can get 16 GB (2 x 8 GB) for $39 (plus shipping and tax) from OWC. Crucial doesn't carry RAM for that machine.


https://eshop.macsales.com/shop/memory/iMac/Retina-5K2015/DDR3L


Install memory in an iMac - Apple Support



Jul 12, 2023 7:38 AM in response to Servant of Cats

Servant of Cats wrote:


HWTech wrote:

But running macOS with just 4GB of RAM will be extremely limiting, but Ok for just the most basic of tasks.

I take it that this 27" iMac had 8 GB (2 x 4 GB), and now has only 4 GB (1 x 4 GB). That means there are three open slots.

You can get 16 GB (2 x 8 GB) for that machine for $39 (plus shipping and tax) from OWC. (Crucial doesn't carry any RAM upgrades for that machine at the moment.) So that would give the OP either 16 or 20 GB (20 GB if one put the working 4 GB module in the second memory bank).

https://eshop.macsales.com/shop/memory/iMac/Retina-5K2015/DDR3L

Install memory in an iMac - Apple Support


yup, this is what I am gonna go for, thank you for the suggestion!

Jul 6, 2023 12:00 PM in response to kirsteeee

What is the make & model of the keyboard you are using with this iMac? For troubleshooting purposes, do you have a spare keyboard you can use? The kernel panic report indicated that the last device that was loaded appears to be a keyboard driver.


Having a newer version of macOS should not be the issue here. Your Late 2015 can be fully upgraded to macOS Monterey.

Jul 6, 2023 12:21 PM in response to Tesserax

I typically use an apple Bluetooth keyboard but currently I also have a wired keyboard attached to the Mac (I experimented with installing ubuntu as a workaround and needed a wired keyboard). I don't have the details of the wired keyboard to hand but I can unplug it, it isn't required. The restarts were happening before I added the wired keyboard.

Jul 6, 2023 3:52 PM in response to Tesserax

So I got fed up of the Mac crashing everytime I tried to reinstall the latest OS, I'm not bothered if the OS is Apple or Linux so I thought I would just replace it with Ubuntu, I then found an alternative way to install Big sur with a USB key, as I mentioned before, I thought I needed to revert to an older OS. So I abandoned the ubuntu plan, reformatted the drive and installed Big sur.

Jul 6, 2023 5:10 PM in response to kirsteeee

https://kb.vmware.com/s/article/1005184 has some background on Machine Check errors thrown by Intel CPUs.


"Recent CPUs from Intel and AMD implement a machine-check architecture that detects and reports hardware issues, including system bus errors, RAM (ECC and parity) errors, and other CPU errors. There are a set of model-specific registers (MSRs) that are used to report errors."


The IA32_MC4_STATUS=0xBE00000000800400 appears to be a bank-specific status. I didn't try to decode the error fully, but it appears that the UC and PCC bits are set, indicating that the processor did not or was not able to correct the error condition, and that the processor state may have been corrupted by the error.



Jul 11, 2023 7:16 AM in response to kirsteeee

kirsteeee wrote:

Any ideas from the etrecheck output?

Most likely a hardware issue of some sort as pointed out by @Servant of Cats. Possibly could be bad memory. You can try removing one memory module to see if the Kernel Panics stop. If you still get them, reinstall the memory module and remove the other memory module. It is unusual for two memory modules to fail at the same time. But running macOS with just 4GB of RAM will be extremely limiting, but Ok for just the most basic of tasks.


Could also be an externally connected device so disconnect all external devices in case one of them is causing a problem.


If it isn't one of these, then most likely the Logic Board will need to be replaced unless it is a power related failure due to the power supply. No good way to really be sure. Probably time to retire this iMac if memory or an external device is not causing the problem.

Jul 12, 2023 7:25 AM in response to kirsteeee

You're welcome. If you want to replace that memory module, then get it from either Crucial or OWC. Make sure to only get the exact part numbers recommended by the tools on their respective sites for identifying compatible parts. With Crucial...the memory is usually listed as "Mac Compatible" or "For Mac" on the website and will also show it on the plastic packaging when you receive the memory (at least they still did last year). Macs are very picky about the memory used, so make sure to only get the exact part numbers suggested by either of these two sites.

Kernel Panic report, Imac late 2015

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