TBT3-UDZ crashes MacBook Pro 16" when plugging in

Whenever I connect my MBP 16" to the TBT3-UDZ it starts detecting everything (external monitor via DP, audio interface, keyboard) but then the laptop shuts off with a loud blast from the fans and then powers down.

After it reboots and I’m back up and running I can actually unplug and reconnect the cable to the dock without it rebooting though. It seems to only happen when coming back from sleep.

I’m up to date on macOS, using the included cable with the dock, plugging into the right side of the MBP, and not using any front panel ports on the dock.

Another odd behavior is that when the laptop is at the macOS lock screen I can’t actually use either the external keyboard or even the internal keyboard to type my login password. It actually doesn’t respond to certain keystrokes on either. Super weird. If I unplug the dock the internal keyboard starts working again.

When using other TB3 or USB-C docks/dongles with basically the same setup it almost never causes any complications, but I’m not sure what else I can directly look at with the Plugable device to start troubleshooting. Are there any firmware updates that need to be applied?

I’ll update this as I test more–it’s just difficult to have to troubleshoot every time I plug in to get some work done when I have limited time to do so.

I experienced the same thing. I just received my TBT3-UDZ and have it set up yesterday. It detected everything, external monitor, audio, NIC, etc. My MBP 16 has been randomly shutting down with a loud blast from the fan at least 4 times. It seems to be coincide with the laptop waking up from sleep or going into sleep. I am not sure which since I hit the keyboard as soon as the display went to black in order to prevent it from sleeping.

I have had my laptop for over a month, and it never did that. And it started doing that after I plugged it into the TBT3-UDZ.

Hello @tf5bassist and @ictoaln,

Thank you for contacting Plugable support! Sorry to hear about these crashing issues. I’d be more than happy to assist.

There have been increased reports of crashing when connecting docks like our TBT3-UDZ. Currently we do not have a solution, but we believe the issue started happening after macOS 11.4.

There is a discussion on the Apple Developer threads mentioning similar issues, and thus far it appears the regression causing the crashing is still present in macOS 11.5 betas. https://developer.apple.com/forums/thread/678644

For the moment, there is likely not much that can be done except to downgrade to an older macOS version (not a trivial task, so I expect most users will be unable to do so), or wait until the next OS release and see if the issue has been resolved.

You may attempt to perform an SMC and PRAM/NVRAM reset, some users have reported this has helped:

  1. Unplug the dock from the Mac
  2. Perform an SMC reset: https://support.apple.com/en-us/HT201295
  3. Perform an NVRAM/PRAM reset: https://support.apple.com/en-us/HT204063
  4. Plug the dock back in to the Mac and see if the behavior has improved

I would also recommend submitting a bug report to Apple. The more users reporting the issue, the better chance it will be resolved in a future update: https://www.apple.com/feedback/macos.html

Please don’t hesitate to let us know of other questions.

Thanks again for contacting Plugable support and best wishes!

Joshua Henry

Senior Engineer | Product Owner
Plugable Technologies

Thanks for the quick response. Yeah, it does seem that a more recent-ish version of macOS might have made this more frequent. Definitely a bummer.

I’ve been submitting the crash reports every time, so maybe that will do a modicum of good here. Maybe at some point, I’ll get around to doing the SMC and NVRAM resets and see if that helps.

And at least two users in that support thread do mention that macOS 12 Monterey beta seems to resolve the issue, so, fingers crossed on that one then!

1 Like

Same/similar problem here (registered just to chime in). Running 11.4.

It started after the macbook had been in sleep for the weekend. Then it crashed when I used the keyboard (connected to the dock) to wake it up. Then I got stuck in a boot-loop where it would keep rebooting until i disconnected the dock. Even once booted, I tried connecting the dock and it would still crash a few seconds later (when display would try to switch). Then I realized that as long as I did not have the display connected it would work fine. If the display was connected, the Macbook would crash within ~5 seconds, or during boot-up.

I had a separate USB-C to HDMI dongle that I was able to successfully use, and then after an hour or so of using that successfully I connected the display back to the second HDMI port on the dock and I have been using that successfully for a few hours now. Still concerned about trying the first port again but will once I am at a stopping point for work.

I’ve been disconnecting my audio interface whenever I’ve reconnected and believed that had stopped the crashes until today.

Left the laptop connected from last night, turned off external monitor, device went to sleep, disconnected audio interface, woke up device today. Turned on external monitor, device froze and restarted.

Had to disconnect dock from laptop in order to actually type my password (second behavior issue mentioned in OP), device rebooted, reconnected dock, external monitor not receiving signal, turned monitor off/on, signal detected. Plugged audio interface back in. So it doesn’t seem to be the interface.

Here’s the crash dump being submitted in case anyone knows this stuff better than I do.

panic(cpu 8 caller 0xffffff8018a9f846): [kext.kalloc.2048]: element modified after free (off:1584, val:0x0000210100000000, sz:2048, ptr:0xffffff9376b85800, prot:zero)
 1584: 0x0000210100000000
 1592: 0x0000000b00000c00
 1600: 0x000000010000000d
 1608: 0x0000061f00000000
 1616: 0x0000028a00000154
 1624: 0x0000001000000a00
 1672: 0xfffffffe00000000
Backtrace (CPU 8), Frame : Return Address
0xffffffb0e31cb470 : 0xffffff801828e0dd 
0xffffffb0e31cb4c0 : 0xffffff80183d4f33 
0xffffffb0e31cb500 : 0xffffff80183c552a 
0xffffffb0e31cb550 : 0xffffff8018232a2f 
0xffffffb0e31cb570 : 0xffffff801828d8fd 
0xffffffb0e31cb690 : 0xffffff801828dbf3 
0xffffffb0e31cb700 : 0xffffff8018a9d81a 
0xffffffb0e31cb770 : 0xffffff8018a9f846 
0xffffffb0e31cbbf0 : 0xffffff80182ecad6 
0xffffffb0e31cbc60 : 0xffffff801829d6bc 
0xffffffb0e31cbcb0 : 0xffffff801829e56b 
0xffffffb0e31cbcd0 : 0xffffff801ae7b60f 
0xffffffb0e31cbde0 : 0xffffff8018560cd2 
0xffffffb0e31cbe10 : 0xffffff8018555294 
0xffffffb0e31cbea0 : 0xffffff80188bd25d 
0xffffffb0e31cbf30 : 0xffffff801831a3bd 
0xffffffb0e31cbf60 : 0xffffff801831969f 
0xffffffb0e31cbfa0 : 0xffffff801823213e 
      Kernel Extensions in backtrace:

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

Mac OS version:

Kernel version:
Darwin Kernel Version 20.5.0: Sat May  8 05:10:33 PDT 2021; root:xnu-7195.121.3~9/RELEASE_X86_64
Kernel UUID: 52A1E876-863E-38E3-AC80-09BBAB13B752
KernelCache slide: 0x0000000018000000
KernelCache base:  0xffffff8018200000
Kernel slide:      0x0000000018010000
Kernel text base:  0xffffff8018210000
__HIB  text base: 0xffffff8018100000
System model name: MacBookPro16,1 (Mac-E1008331FDC96864)
System shutdown begun: NO
Hibernation exit count: 22

System uptime in nanoseconds: 248563489477484
Last Sleep:           absolute           base_tsc          base_nano
  Uptime  : 0x0000e211327e966f
  Sleep   : 0x0000a5e722688836 0x000051c4c604fe6a 0x0000a5c35de6437f
  Wake    : 0x0000a5e755430356 0x0000578a2ceca244 0x0000a5e7347d5edd
last started kext at 248518503547657: >!UAudio	405.39 (addr 0xffffff7fb2da6000, size 315392)
last stopped kext at 203888360236780: >!UAudio	405.39 (addr 0xffffff7fb2da6000, size 315392)
loaded kexts:
org.virtualbox.kext.VBoxNetAdp	6.1.22
org.virtualbox.kext.VBoxNetFlt	6.1.22
org.virtualbox.kext.VBoxUSB	6.1.22
org.virtualbox.kext.VBoxDrv	6.1.22
>AudioAUUC	1.70
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>!ABCMWLANBusInterfacePCIeMac	1
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Hello @tf5bassist

Thanks for the update. Looking at the crash dump there I’m not seeing anything particularly conclusive. The extension in the backtrace was for “com.apple.iokit.IOStorageFamily” which I do not think should crash from connecting the dock. I have seen this before in some other crash dumps, but it’s not in all of them, usually I’m seeing extensions related to the graphics system.

Another option to explore at this time, macOS 11.5 was just released and we’re already hearing from some customers that various issues appear to have been resolved with this most recent update. I’d be curious to hear if applying the update may help in this case.

I have exactly the same behavior. I have two pluggable docking stations (both tbt3-udz). One at home and one in the office. And both of them randomly switch off my Mac on boot. I noticed something (Mac or dock station) trying to switch on one of the monitors. When it attempted to switch on the second one it got stuck for several seconds then was rebooting. Last time it reboots about 5 times before it switches on.

Just an update. Nothing has changed since the last MacOS release (Big Sur 11.5).

panic(cpu 1 caller 0xffffff801ea9fc36): [kext.kalloc.2048]: element modified after free (off:1584, …

Thank you for the update, sorry to hear that 11.5 has not helped for you, @Alex84.

We’re currently getting our 2019 16" MacBook Pro updated to 11.5.1 (just released today) to see if we can also still reproduce the crashing. I’ll post an update with our testing results. (We were able to reproduce the issue with 11.4 for reference.)

Best wishes,