Big Sur panic when connect/disconnect usb-c dock

Same problem - multiple crashes per day. Crashes often occur in display driver (com.apple.kext.AMDRadeonX6000Framebuffer), but not always.

How is it possible to have less stable drivers on mac than on windows, when windows has to support 1000s of hardware configurations? This is embarrassing.

Having the same issue reboot due to Kernel panic 🤬🤬🤬 apple support just recommended reinstall OS 🤦‍♂️

MacBook Pro (16-inch, 2019) current MacOS Big Sur 11.6 (the issue still observed) Dell Thunderbolt Dock WD19TB

panic(cpu 4 caller 0xffffff800b89fc36): [kext.kalloc.2048]: element modified after free (off:1672, val:0xffffffff00000000, sz:2048, ptr:0xffffff9383b7f000, prot:zero)  1672: 0xffffffff00000000

I am having the same issue using a Dock station Lenovo Thinkpad after the upgrade to the BigSur version.

panic(cpu 8 caller 0xffffff8004c9edf6): [kext.kalloc.2048]: element modified after free (off:1672, val:0xfffffffe00000000, sz:2048, ptr:0xffffff9361e6d000, prot:zero)
 1672: 0xfffffffe00000000
Backtrace (CPU 8), Frame : Return Address
0xffffffb0cdc9acf0 : 0xffffff800448cfdd 
0xffffffb0cdc9ad40 : 0xffffff80045d3fd3 
0xffffffb0cdc9ad80 : 0xffffff80045c45ca 
0xffffffb0cdc9add0 : 0xffffff8004431a2f 
0xffffffb0cdc9adf0 : 0xffffff800448c7fd 
0xffffffb0cdc9af10 : 0xffffff800448caf3 
0xffffffb0cdc9af80 : 0xffffff8004c9cdca 
0xffffffb0cdc9aff0 : 0xffffff8004c9edf6 
0xffffffb0cdc9b470 : 0xffffff80044eb976 
0xffffffb0cdc9b4e0 : 0xffffff800449c5ec 
0xffffffb0cdc9b530 : 0xffffff8004bada32 
0xffffffb0cdc9b550 : 0xffffff7f9e8fefe2 
0xffffffb0cdc9b600 : 0xffffff7f9e8ff672 
0xffffffb0cdc9b640 : 0xffffff7f9e8bfc62 
0xffffffb0cdc9b660 : 0xffffff7f9f1f9e78 
0xffffffb0cdc9b900 : 0xffffff7f9e8c0800 
0xffffffb0cdc9b930 : 0xffffff7f9f1fb074 
0xffffffb0cdc9b9c0 : 0xffffff7f9f1f90f7 
0xffffffb0cdc9ba10 : 0xffffff7f9f1f8ee7 
0xffffffb0cdc9ba60 : 0xffffff7f9f1f7f99 
0xffffffb0cdc9baa0 : 0xffffff8004c1d67e 
0xffffffb0cdc9baf0 : 0xffffff7f9e8c04be 
0xffffffb0cdc9bb20 : 0xffffff8004c2792b 
0xffffffb0cdc9bc80 : 0xffffff800457f7d1 
0xffffffb0cdc9bd90 : 0xffffff800449265d 
0xffffffb0cdc9be00 : 0xffffff8004468cd5 
0xffffffb0cdc9be60 : 0xffffff80044801e2 
0xffffffb0cdc9bef0 : 0xffffff80045a869d 
0xffffffb0cdc9bfa0 : 0xffffff8004432216 
      Kernel Extensions in backtrace:

Same issue here. Happens around 5-10 times a month when I connect external Dell U2719DC monitor via USB C:

panic(cpu 2 caller 0xffffff801669edf6): [kext.kalloc.2048]: element modified after free (off:1672, val:0xfffffffe00000000, sz:2048, ptr:0xffffff937592b800, prot:zero)
 1672: 0xfffffffe00000000
Backtrace (CPU 2), Frame : Return Address
0xffffffa0e2052cf0 : 0xffffff8015e8cfdd 
0xffffffa0e2052d40 : 0xffffff8015fd3fd3 
0xffffffa0e2052d80 : 0xffffff8015fc45ca 
0xffffffa0e2052dd0 : 0xffffff8015e31a2f 
0xffffffa0e2052df0 : 0xffffff8015e8c7fd 
0xffffffa0e2052f10 : 0xffffff8015e8caf3 
0xffffffa0e2052f80 : 0xffffff801669cdca 
0xffffffa0e2052ff0 : 0xffffff801669edf6 
0xffffffa0e2053470 : 0xffffff8015eeb976 
0xffffffa0e20534e0 : 0xffffff8015e9c5ec 
0xffffffa0e2053530 : 0xffffff80165ada32 
0xffffffa0e2053550 : 0xffffff7fb02fefe2 
0xffffffa0e2053600 : 0xffffff7fb02ff672 
0xffffffa0e2053640 : 0xffffff7fb02bfc62 
0xffffffa0e2053660 : 0xffffff7fb0bf9e78 
0xffffffa0e2053900 : 0xffffff7fb02c0800 
0xffffffa0e2053930 : 0xffffff7fb0bfb074 
0xffffffa0e20539c0 : 0xffffff7fb0bf90f7 
0xffffffa0e2053a10 : 0xffffff7fb0bf8ee7 
0xffffffa0e2053a60 : 0xffffff7fb0bf7f99 
0xffffffa0e2053aa0 : 0xffffff801661d67e 
0xffffffa0e2053af0 : 0xffffff7fb02c04be 
0xffffffa0e2053b20 : 0xffffff801662792b 
0xffffffa0e2053c80 : 0xffffff8015f7f7d1 
0xffffffa0e2053d90 : 0xffffff8015e9265d 
0xffffffa0e2053e00 : 0xffffff8015e68cd5 
0xffffffa0e2053e60 : 0xffffff8015e801e2 
0xffffffa0e2053ef0 : 0xffffff8015fa869d 
0xffffffa0e2053fa0 : 0xffffff8015e32216 
      Kernel Extensions in backtrace:
         com.apple.iokit.IOAcceleratorFamily2(442.9)[065DAA9E-DE99-3C6D-A8D6-06BFD26CA1DC]@0xffffff7fb0bb4000->0xffffff7fb0c1efff
            dependency: com.apple.driver.AppleMobileFileIntegrity(1.0.5)[A994AEFE-3919-310E-A2C9-405E864BCB7B]@0xffffff80174c0000->0xffffff80174d5fff
            dependency: com.apple.iokit.IOGraphicsFamily(585.1)[240F08CD-4BC4-3093-8832-0E899EFC14F4]@0xffffff7fb0d35000->0xffffff7fb0d63fff
            dependency: com.apple.iokit.IOPCIFamily(2.9)[4E85D41F-6AD7-3C24-911C-A8B80B599F86]@0xffffff801896c000->0xffffff8018994fff
            dependency: com.apple.iokit.IOReportFamily(47)[77F098F2-012A-32EF-BD19-8A0E7ADF46E9]@0xffffff80189a3000->0xffffff80189a5fff
            dependency: com.apple.iokit.IOSurface(290.8.1)[3BE6ED95-B932-3F71-9DD5-4563CF4BD0DC]@0xffffff8018a96000->0xffffff8018ab2fff
         com.apple.driver.AppleIntelKBLGraphics(16.0.5)[493FBA7F-5361-30A7-9A49-57162C8351AD]@0xffffff7fb02a9000->0xffffff7fb0360fff
            dependency: com.apple.iokit.IOAcceleratorFamily2(442.9)[065DAA9E-DE99-3C6D-A8D6-06BFD26CA1DC]@0xffffff7fb0bb4000->0xffffff7fb0c1efff
            dependency: com.apple.iokit.IOGraphicsFamily(585.1)[240F08CD-4BC4-3093-8832-0E899EFC14F4]@0xffffff7fb0d35000->0xffffff7fb0d63fff
            dependency: com.apple.iokit.IOPCIFamily(2.9)[4E85D41F-6AD7-3C24-911C-A8B80B599F86]@0xffffff801896c000->0xffffff8018994fff
            dependency: com.apple.iokit.IOSurface(290.8.1)[3BE6ED95-B932-3F71-9DD5-4563CF4BD0DC]@0xffffff8018a96000->0xffffff8018ab2fff

Process name corresponding to current thread: WindowServer
Boot args: chunklist-security-epoch=0 -chunklist-no-rev2-dev chunklist-security-epoch=0 -chunklist-no-rev2-dev

Mac OS version:
20G165

Kernel version:
Darwin Kernel Version 20.6.0: Mon Aug 30 06:12:21 PDT 2021; root:xnu-7195.141.6~3/RELEASE_X86_64

Lo and behold. Disabling DisplayPort 1.2 in my monitor solved the issue for me. This was suggested as a fix by others in comments to earlier messages. I used to have consistent crashes once or twice per day, typically shortly after powering on the monitor. I disabled DisplayPort 1.2 five days ago and have not had a single crash since.

My specs for those interested:

• MacBook Pro (16-inch, 2019) with AMD Radeon Pro 5500M 4 GB
• Monitor: Dell U3014 30", connected with USB-C to DisplayPort cable (no hubs or adapters)

I've been having the same issue. Dell monitors have this weird features such as MST and DP 1.2. Turn it off and see if it works see full list: https://www.dell.com/community/Monitors/Single-monitor-on-a-PC-MST-Off-DisplayPort-1-2-Disable/td-p/6131242

(you turn this off in the screen options that is built in, not on the mac)

Model Name:	MacBook Pro (13-inch, 2020, Four Thunderbolt 3 ports)
Model Identifier:	MacBookPro16,2
Processor Name:	Quad-Core Intel Core i5
Processor Speed:	2 GHz
Number of Processors:	1
Total Number of Cores:	4
L2 Cache (per Core):	512 KB
L3 Cache:	6 MB
Hyper-Threading Technology:	Enabled
Memory:	32 GB

Still experiencing this issue and this is not while I'm connected to an external display. It happens when I spin up Docker for work and when I attempt to do something else that requires streaming i.e. pairing on a task via something like Tuple or Slack or even streaming YouTube music.

This has also happened when connected to an external display and/or connected via SideCar to my iPad

+1 on all of that. Crashes AT LEAST once a day. Thankfully to this thread I can save myself a trip to the apple store.

HI, I see the last incidence of this was from 5 months ago, but I'm having it. I have updated my mac to the latest version (11.6) and it systematically reboots when the laptop is closed (sleeping) and I connect it to a DELL dock. Here's the report.

panic(cpu 5 caller 0xffffff8000e9edf6): [kext.kalloc.2048]: element modified after free (off:1672, val:0xfffffffe00000000, sz:2048, ptr:0xffffff937a255800, prot:zero) 1672: 0xfffffffe00000000 Backtrace (CPU 5), Frame : Return Address 0xffffffa12a1929b0 : 0xffffff800068cfdd 0xffffffa12a192a00 : 0xffffff80007d3fd3 0xffffffa12a192a40 : 0xffffff80007c45ca 0xffffffa12a192a90 : 0xffffff8000631a2f 0xffffffa12a192ab0 : 0xffffff800068c7fd 0xffffffa12a192bd0 : 0xffffff800068caf3 0xffffffa12a192c40 : 0xffffff8000e9cdca 0xffffffa12a192cb0 : 0xffffff8000e9edf6 0xffffffa12a193130 : 0xffffff80006eb976 0xffffffa12a1931a0 : 0xffffff800069c5ec 0xffffffa12a1931f0 : 0xffffff8000dada32 0xffffffa12a193210 : 0xffffff800375d84c 0xffffffa12a193230 : 0xffffff800376bb08 0xffffffa12a193290 : 0xffffff800375dfd4 0xffffffa12a193330 : 0xffffff80037600a7 0xffffffa12a1935e0 : 0xffffff800375e4d9 0xffffffa12a193740 : 0xffffff8003755981 0xffffffa12a193c50 : 0xffffff8000e86af4 0xffffffa12a193ce0 : 0xffffff8000920e40 0xffffffa12a193d40 : 0xffffff8000936d56 0xffffffa12a193f40 : 0xffffff8000d3f1de 0xffffffa12a193fa0 : 0xffffff80006321f6 Kernel Extensions in backtrace: com.apple.security.sandbox(300.0)[1E5C48E7-0D4C-30DA-BFA4-C87B27353F0D]@0xffffff800374c000->0xffffff8003792fff dependency: com.apple.driver.AppleMobileFileIntegrity(1.0.5)[A994AEFE-3919-310E-A2C9-405E864BCB7B]@0xffffff8001cc0000->0xffffff8001cd5fff dependency: com.apple.iokit.IOStorageFamily(2.1)[7C0E4949-640F-3D1D-97AF-030903A22663]@0xffffff800326f000->0xffffff8003280fff dependency: com.apple.kext.AppleMatch(1.0.0d1)[EAD07327-D5B8-36D8-B3CC-DBEE8E4EE295]@0xffffff8001cbc000->0xffffff8001cbefff

Process name corresponding to current thread: NotificationCenter Boot args: chunklist-security-epoch=0 -chunklist-no-rev2-dev chunklist-security-epoch=0 -chunklist-no-rev2-dev

Mac OS version: 20G165

Kernel version: Darwin Kernel Version 20.6.0: Mon Aug 30 06:12:21 PDT 2021; root:xnu-7195.141.6~3/RELEASE_X86_64 Kernel UUID: C2591F4E-EE82-33CC-8C59-DB81D9AD80DD KernelCache slide: 0x0000000000400000 KernelCache base: 0xffffff8000600000 Kernel slide: 0x0000000000410000 Kernel text base: 0xffffff8000610000 __HIB text base: 0xffffff8000500000 System model name: MacBookPro16,1 (Mac-E1008331FDC96864) System shutdown begun: NO Hibernation exit count: 26

System uptime in nanoseconds: 17717902905029 Last Sleep: absolute base_tsc base_nano Uptime : 0x0000101d454f11d3 Sleep : 0x0000101acfea5760 0x000009c937ae70e6 0x000010050575280f Wake : 0x0000101b01527036 0x00000a14da9d9e62 0x0000101ae0a7ca49 last started kext at 12580617391: >AGPM 122.1 (addr 0xffffff7f99da9000, size 118784) loaded kexts:

AGPM 122.1 !APlatformEnabler 2.7.0d0 X86PlatformShim 1.0.0

@filesystems.autofs 3.0 @fileutil 20.036.15

AudioAUUC 1.70 !ATopCaseHIDEventDriver 4050.1 !AHIDALSService 1

@kext.AMDRadeonX6000 4.0.6 @kext.AMDRadeonServiceManager 4.0.6

!AGraphicsDevicePolicy 6.3.5 !AUpstreamUserClient 3.6.8

@AGDCPluginDisplayMetrics 6.3.5

pmtelemetry 1

|IOUserEthernet 1.0.1

!ABridgeAudio!C 140.4 !AFIVRDriver 4.1.0 ACPI_SMC_PlatformPlugin 1.0.0 usb.!UUserHCI 1 BridgeAudioCommunication 140.4 !AGFXHDA 100.1.433 !AAVEBridge 6.1 !AThunderboltIP 4.0.3 !A!IKBLGraphics 16.0.5

|IO!BSerialManager 8.0.5d7 @Dont_Steal_Mac_OS_X 7.0.0

!AHV 1 !ADiskImages2 1 !AMuxControl2 6.3.5 !AWWANSupport1 4.0.0 !A!ICFLGraphicsFramebuffer 16.0.5 !A!IPCHPMC 2.0.1 AGDCBacklightControl 6.3.5 !ABacklight 180.3 !AMCCSControl 1.14 !A!ISlowAdaptiveClocking 4.0.0 !AWWANSupport 4.0.0 usb.realtek8153patcher 5.0.0 BCMWLANFirmware4378.Hashstore 1 BCMWLANFirmware4377.Hashstore 1 BCMWLANFirmware4364.Hashstore 1 BCMWLANFirmware4355.Hashstore 1 !AFileSystemDriver 3.0.1

@filesystems.tmpfs 1 @filesystems.hfs.kext 556.100.11 @BootCache 40 @!AFSCompression.!AFSCompressionTypeZlib 1.0.0 @!AFSCompression.!AFSCompressionTypeDataless 1.0.0d1

!ABCMWLANBusInterfacePCIeMac 1

@filesystems.apfs 1677.141.2 @private.KextAudit 1.0

!ASmartBatteryManager 161.0.0 !AACPIButtons 6.1 !ASMBIOS 2.1 !AACPIEC 6.1 !AAPIC 1.7

@!ASystemPolicy 2.0.0 @nke.applicationfirewall 311 |IOKitRegistryCompatibility 1 |EndpointSecurity 1 @kext.triggers 1.0

!AHIDKeyboard 224 !AActuatorDriver 4440.3 !AMultitouchDriver 4440.3 !AInputDeviceSupport 4400.35 !AHS!BDriver 4050.1 IO!BHIDDriver 8.0.5d7

@kext.AMDRadeonX6100HWLibs 1.0 @kext.AMDRadeonX6000HWServices 4.0.6

IOPlatformPluginLegacy 1.0.0 X86PlatformPlugin 1.0.0 usb.cdc.acm 5.0.0 usb.serial 6.0.0

|IO!BHost!CUARTTransport 8.0.5d7 |IO!BHost!CTransport 8.0.5d7 @kext.AMDRadeonX6000Framebuffer 4.0.6 @kext.AMDSupport 4.0.6

!AHDA!C 283.15

|IOHDA!F 283.15

!AThunderboltEDMSink 5.0.3

|IOAVB!F 940.4 |IOEthernetAVB!C 1.1.0

!AGraphicsControl 6.3.5

|IOAccelerator!F2 442.9

IOPlatformPlugin!F 6.0.0d8

@!AGPUWrangler 6.3.5 @!AGraphicsDeviceControl 6.3.5

!ABacklightExpert 1.1.0

|IONDRVSupport 585.1 |IOGraphics!F 585.1

!ASMBus!C 1.0.18d1

@plugin.IOgPTPPlugin 985.2

!UAudio 405.39

|IOAudio!F 300.6.1 @vecLib.kext 1.2.0

!ASMBusPCI 1.0.14d1 !A!ILpssUARTv1 3.0.60 !A!ILpssUARTCommon 3.0.60 !AOnboardSerial 1.0

I was able to fix this panic by disabling "DP Daisy Chain" in monitor options. Was experiencing daily crashes after unplugging monitor, which was black after "unsuccessful" connection. My specs:

• MacBook Pro (16-inch, 2019), 2.6 GHz 6-Core Intel Core i7, 32 GB 2667 MHz DDR4, AMD Radeon Pro 5300M 4 GB
• Lenovo P24h-10 via Type-c

I connect my Macbook pro(16 inch with BigSur 11.6) to Dell P2717HC monitor through usb c type.
Macbook pro crashes unexpectedly and even I tried to reconnect 2-3 times continuously.

After I changed MST to off in my Dell monitor Display option. I tried to plug and unplug usb c type connectivity 10 times in my Macbook pro, I have not faced crashing.

I have been encountering this problem in my Macbook Pro 16" i7 and it was really frustrating.

I would like to share that it never happen again after I upgraded to OSX Monterey. I can now connect my Macbook and it works fine, regardless if it is sleeping or not.

Monterey is still not released officially but the beta is beta available for developer & public preview. If you dont want to go unofficial, just hold tight and sooner, this thread will be closed (hopefully).

Same here, 16" MBP (2019) and Radeon Pro 5500M 8GB; I keep encountering the same crash message when I connect my monitor via one of the DP ports on my HP Thunderbolt 3 Dock G2. The dock firmware is up to date. Using the Thunderbolt port to connect my monitor will not cause any crashes.

My 15" MBP (2017) is rock solid with the same dock & monitor setup, no matter how many times I plug and unplug, there are no crashes at all.

I've had the same issue for well over a year - though at least two of three majors versions of the OS ... but the panic has moved to different stack traces - initially in the AMD driver, and not in com.apple.WebKit.Networking ... I can just about re-produce this issue on demand. I'm running dual 4k monitors via DisplayPort, both connected to a CalDigit USB-C Pro dock. I've been in active communication with CalDigit about the issue, and of course, they say it's an apple issue.

I've conducted an experiment -  I got two different brands for USB-C to DisplayPort adaptors, and ran one monitor via the Thunderbolt 3 USB-C Pro Dock, and one via an adaptor directly connected to to a second USB-C port of the MacBook Pro. I did not have a single panic, nor did I have issues with the mac detecting both displays for a couple weeks. (I also ran with both displayPort monitors on USB-C-DisplayPort adaptors, and none connected to the dock, without panics.)

Last night, I put the second display back on the USB-C Pro Dock. Within 12- hours … I now have had a mis-sync of the monitors … one monitor detected, the other was not. Disconnecting and reconnecting the displayPort on the missing monitor - both monitors got detected, but then 1-2 minutes later - the system panicked within the com.apple.WebKit.Networking thread.

I've send nearly every single one in on a report, and was putting additional comments on how to reproduce ... it's annoying that this is continuing.

The work around, of course, seem to simply not do single cable, dual-monitor docking. I'm eye some of the eGPU chassises, as I already have some AMD 580s laying around, from a retired hackintosh experiment, currious if this would bypass the issue. It seems to indicate to me, that this is something to do specially with the USB-C DisplayPort™ Alternate Mode when using the dual channels on a single cable.

But why com.apple.WebKit.Networking ?

panic(cpu 2 caller 0xffffff800b09edf6): [kext.kalloc.2048]: element modified after free (off:1672, val:0xfffffffe00000000, sz:2048, ptr:0xffffff9366d74800, prot:zero)
 1672: 0xfffffffe00000000
[ … ]
0xffffffb0d4c3bfa0 : 0xffffff800a8321f6 
   Kernel Extensions in backtrace:
     com.apple.security.sandbox(300.0)[1E5C48E7-0D4C-30DA-BFA4-C87B27353F0D]@0xffffff800d94c000->0xffffff800d992fff
      dependency: com.apple.driver.AppleMobileFileIntegrity(1.0.5)[A994AEFE-3919-310E-A2C9-405E864BCB7B]@0xffffff800bec0000->0xffffff800bed5fff
      dependency: com.apple.iokit.IOStorageFamily(2.1)[7C0E4949-640F-3D1D-97AF-030903A22663]@0xffffff800d46f000->0xffffff800d480fff
      dependency: com.apple.kext.AppleMatch(1.0.0d1)[EAD07327-D5B8-36D8-B3CC-DBEE8E4EE295]@0xffffff800bebc000->0xffffff800bebefff

Process name corresponding to current thread: com.apple.WebKit.Networking
Boot args: chunklist-security-epoch=0 -chunklist-no-rev2-dev

Mac OS version:
20G165

Model Name:	MacBook Pro
 Model Identifier:	MacBookPro16,1
 Processor Name:	6-Core Intel Core i7
  Processor Speed:	2.6 GHz
AMD Radeon Pro 5300M:
Chipset Model:	AMD Radeon Pro 5300M

I've been having the same issue. Dell monitors have this weird features such as MST and DP 1.2. Turn it off and see if it works see full list: https://www.dell.com/community/Monitors/Single-monitor-on-a-PC-MST-Off-DisplayPort-1-2-Disable/td-p/6131242

(you turn this off in the screen options that is built in, not on the mac)

This did help for me, for people who may not see.