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Kenel panic after updated to Big Sur 11.1 when shutdown my iMac

I have updated my macOS to Big Sur 11.1 recently, but sometimes when I want to shutdown my iMac, it fails and it will restart and the following log info will pop up, can anyone know how to fix it? I knew it's kernel panic, and I have disconnected all USB devices when I want to shutdown my iMac, but the problem still exist.




panic(cpu 1 caller 0xffffff800356e9fe): watchdog timeout: no checkins from watchdogd in 301 seconds (413 totalcheckins since monitoring last enabled), shutdown in progress

Backtrace (CPU 1), Frame : Return Address

0xffffffa054f53c00 : 0xffffff80002b9aed

0xffffffa054f53c50 : 0xffffff80003fc6e3

0xffffffa054f53c90 : 0xffffff80003ecd1a

0xffffffa054f53ce0 : 0xffffff800025ea2f

0xffffffa054f53d00 : 0xffffff80002b938d

0xffffffa054f53e20 : 0xffffff80002b9678

0xffffffa054f53e90 : 0xffffff8000abe434

0xffffffa054f53f00 : 0xffffff800356e9fe

0xffffffa054f53f20 : 0xffffff800356e304

0xffffffa054f53f50 : 0xffffff80018a39dc

0xffffffa054f53fa0 : 0xffffff800025e13e

Kernel Extensions in backtrace:

com.apple.driver.watchdog(1.0)[7AE04EA4-D026-39A0-B2D5-5C9E4EE72967]@0xffffff800356d000->0xffffff800356efff

com.apple.driver.AppleSMC(3.1.9)[D674490B-26E7-312B-9E8E-03250124CCC6]@0xffffff8001894000->0xffffff80018acfff

dependency: com.apple.driver.watchdog(1)[7AE04EA4-D026-39A0-B2D5-5C9E4EE72967]@0xffffff800356d000->0xffffff800356efff

dependency: com.apple.iokit.IOACPIFamily(1.4)[C8F0E837-965A-3EB4-B8F6-4C2142046028]@0xffffff80026d7000->0xffffff80026d8fff

dependency: com.apple.iokit.IOPCIFamily(2.9)[D0F1BFB8-C28E-3E70-891B-73B783189394]@0xffffff8002c2c000->0xffffff8002c53fff


Process name corresponding to current thread: kernel_task


Mac OS version:

20C69


Kernel version:

Darwin Kernel Version 20.2.0: Wed Dec 2 20:39:59 PST 2020; root:xnu-7195.60.75~1/RELEASE_X86_64

Kernel UUID: 82E2050C-5936-3D24-AD3B-EC4EC5C09E11

KernelCache slide: 0x0000000000000000

KernelCache base: 0xffffff8000200000

Kernel slide: 0x0000000000010000

Kernel text base: 0xffffff8000210000

__HIB text base: 0xffffff8000100000

System model name: iMac18,3 (Mac-BE088AF8C5EB4FA2)

System shutdown begun: YES

Panic diags file available: YES (0x0)

Hibernation exit count: 0


System uptime in nanoseconds: 4420942937875

Last Sleep: absolute base_tsc base_nano

Uptime : 0x0000040554bbc99f

Sleep : 0x0000000000000000 0x0000000000000000 0x0000000000000000

Wake : 0x0000000000000000 0x0000000700ea93dc 0x0000000000000000

last started kext at 3682174645354: >!AXsanScheme 3 (addr 0xffffff8001a66000, size 12288)

last stopped kext at 3744006890021: >!AXsanScheme 3 (addr 0xffffff8001a66000, size 12288)

loaded kexts:

@filesystems.afpfs 11.3

@nke.asp_tcp 8.2

>!ATopCaseHIDEventDriver 4020.6

>AudioAUUC 1.70

>!APlatformEnabler 2.7.0d0

>AGPM 119

>X86PlatformShim 1.0.0

@filesystems.autofs 3.0

>!AUpstreamUserClient 3.6.8

@kext.AMDFramebuffer 4.0.2

@fileutil 20.036.15

@kext.AMDRadeonX4000 4.0.2

@kext.AMDRadeonServiceManager 4.0.2

>!AHDA 283.15

>!AGraphicsDevicePolicy 6.2.2

@AGDCPluginDisplayMetrics 6.2.2




iMac 27″ 5K, macOS 11.1

Posted on Jan 25, 2021 10:23 AM

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Posted on Jan 25, 2021 3:35 PM

You likely have a hardware problem, but it could have been something that BrickMyMac "cleaned" that was a required part of the OS.

You should take it to an Apple Store or Authorized Repair Center to have it evaluated.

It could be some problem with Apple's kexts, but Apple will never figure that out unless people bring in their Macs for testing.


In the rare case it is something within NVRAM, try resetting it.

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Question marked as Top-ranking reply

Jan 25, 2021 3:35 PM in response to lecokey

You likely have a hardware problem, but it could have been something that BrickMyMac "cleaned" that was a required part of the OS.

You should take it to an Apple Store or Authorized Repair Center to have it evaluated.

It could be some problem with Apple's kexts, but Apple will never figure that out unless people bring in their Macs for testing.


In the rare case it is something within NVRAM, try resetting it.

Jan 26, 2021 1:57 AM in response to Luis Sequeira1

Here is how I suggest you do a clean install:




1) VERY IMPORTANT - BACKUP! You are about to erase your system drive. Never do that without a backup - well, actually, you should have at least two... I recommend a Time Machine on one drive, and a full clone of your system drive in a separate one.




2) Download the full  Big Sur installer from the App Store. If the installer starts automatically, quit it.


[if the OS you want to install is an older one, like Catalina, Mojave or High Sierra, use this link instead: https://support.apple.com/en-us/HT211683]




3) Create an installer drive on a thumb drive, following the instructions here:


How to create a bootable installer for macOS - Apple Supportsupport.apple.com › en-us






4) On recent macs, you may need to authorize booting from an external drive, which may be disabled by default. You do this in "Boot Security Utility".


Information about this is available in this support document:




https://support.apple.com/en-us/HT208198




---- do not proceed further without a backup!!!! ---- 






5) Restart your mac holding the Option key, and select that installer disk to boot your mac


6) Use Disk Utility to reformat your internal drive as APFS


7) Quit Disk Utility and start the installer. 


8) When asked, choose to migrate content from "another mac, time machine or drive".


IMPORTANT: elect to migrate ONLY user accounts; NOT applications, settings or other files

Jan 25, 2021 11:33 AM in response to redhead101

Yes, but how are we supposed to figure out what its cause may be? We need information to work on, and the easiest way to get it is by looking at the Etrecheck report that I asked for.

A kernel panic can have two types of causes: hardware failure or software. Without knowing anything about the mac in question and what software it has installed there is very little anyone can do.

Jan 25, 2021 12:17 PM in response to Luis Sequeira1




Major Issues:

    Anything that appears on this list needs immediate attention. 


    Runaway process - A process is using a large percentage of your CPU.


Minor Issues:

    These issues do not need immediate attention but they may indicate future problems or opportunities for improvement. 


    No Time Machine backup - Time Machine backup not found.

    Heavy network usage - This computer has recently restarted and has high network usage.

    Clean up - There are orphan files that could be removed.

    Unsigned files - There are unsigned software files installed. Apple has said that unsigned software will not run by default in a future version of the operating system.

    System modifications - There are a large number of system modifications running in the background.

    32-bit Apps - This computer has 32-bits apps will not work on current versions of the operating system.

    Limited drive access - More information may be available with Full Drive Access.

    Kernel extensions present - This computer has kernel extensions that may not work in the future.

Feb 7, 2021 9:12 AM in response to lecokey

How many disks do you have connected to your computer?

There is a known watchdog kernel panic with many disks. Generally 12 or more, but it can be less.


Watch your drives when you shutdown. They flush their cache Asynchronously, (one at a time), which depending on the drives, takes several seconds. If the amount of time flushing the cache takes more time than watchdog allocates, the system kernel panics.


this has been around for several years.


If this is your problem, then a simple fix is unmount your volumes first.

Kenel panic after updated to Big Sur 11.1 when shutdown my iMac

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