Kernel Panic With 4k 240 Hz External Monitor

<< Apple cannot reproduce the issue... >>

if you have a simple setup and a way way to reproduce the crashing every time in short order, contact support and ask them too ADD that setup to the main Bug Report.

This bug still exists on macOS 15.6.1. I am super disappointed. I pay premium prices for Apple products that are always marketed as “Pro” and “for professionals,” yet they still can’t support 4K 240Hz properly. This has been around for about a year with no fix. Every macOS update I try to enable 240Hz again, and every time it lets me down.

Same. 2-3 crashes per day. Have a Samsung LS49CG932SNXZA with a proper USB certified cable.

panic(cpu 0 caller 0xfffffe0027d03644): DCPEXT1 PANIC - apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() --  - iomfb_mailbox(70)
apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() -- 
RTKit: RTKit-2784.140.9.release - Client: AppleDCP-811.120.13~3320-t602xdcp.RELEASE
!UUID: a1000010-2140-1ed5-a178-80d201401ed5
ASLR slide: 0x000000000005c000
Time: 0x000003d7c050d606

Faulting task  70 Call Stack: 0x000000000007b884 0x000000000007b24c 0x000000000007b058 0x0000000000073cb8 0x00000000001d8298 0x0000000000212060 0x0000000000211dac 0x000000000020f294 0x000000000007bcb8 0x00000000000768b4 000000000000000000
RTKit Task List:
   name                    | pri     | stack use | status     | resource | warning
 0 rtk_background          | 007     |   832/2048  | SEMWAIT    | 0x958600 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x00000000000768b4

 1 rtk_ep_work             | 057     |   904/2048  | SEMWAIT    | 0x954be0 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x00000000000768b4

 2 log_tx                  | 007     |   608/2048  | SEMWAIT    | 0x9416f0 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x00000000000768b4

 3 log_flush               | 015     |   928/4096  | SEMWAIT    | 0x940a90 | 
      0x0000000000075d38 0x0000000000076d6c 0x0000000000082404 0x00000000000768b4

 4 tracekit_work           | 007     |   592/4096  | SEMWAIT    | 0x93e5c0 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x00000000000768b4

 5 power                   | 000     |  1568/65536 | RUNNABLE   | 0x7356a8 | 
      0x0000000000075d38 0x000000000007aa24 0x000000000007a744 0x00000000000768b4

 6 Terminator              | 015     |   416/2048  | SEMWAIT    | 0x92cc90 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x00000000000768b4

 7 main                    | 015     |  8656/40960 | SEMWAIT    | 0x928170 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x000000000006a384 0x000000000006c60c

 8 dcpexpert               | 015     |   240/16368 | SEMWAIT    | 0xffffffff0c011f40 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x00000000000768b4

 9 rtkitpmgr               | 015     |   240/16368 | SEMWAIT    | 0xffffffff0c031f40 | 
      0x0000000000075d38 0x0000000000076d6c 0x000000000007bc4c 0x00000000000768b4

(snip)

I'm also getting this issue on a ROG PG32UCDM:

panic(cpu 1 caller 0xfffffe0017b13410): DCPEXT0 PANIC - apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() --  - iomfb_mailbox(50)
apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() -- 
RTKit: RTKit-2758.1.1.release - Client: AppleDCP-811.1.1~291-t602xdcp.RELEASE
!UUID: a1000010-2140-1ed5-a178-80d201401ed5
ASLR slide: 0x0000000000367000
Time: 0x00000786450ad51f

It seems to occur most frequently when I'm using Discord, which I believe is an app rendering via Electron? I've had some issues with apps like this on Windows too where they behave weird. I wonder is that any clue to the issue?

Anyway, +1 to this needing a fix.

Unfortunately I also got a kernel panic while using 26.1, so indeed nothing has been fixed.

There probably is nothing here for Apple to fix. More than likely you need to use a different higher grade cable.

This is incorrect. The kernel panic happens with Apple's own Thunderbolt 4 cable as well, as already reported in this thread. What even higher grade cable are you referring to?

Users here are seeing this as something Apple accidentally broke, when in fact it is really Apple trying to make things work better for the newer higher resolution HD displays...

This is also incorrect. There is absolutely no excuse for a kernel panic, regardless of the cable used. This is a serious issue in the code, which can and should be fixed. Connection with a poor quality cable may be unstable, may flicker, may disconnect every other second, etc. but the kernel may not crash like this but has to fail gracefully. It's pointless to come up with excuses why Apple shouldn't fix this because it's the user's fault. It's not the user's fault. And I know my stuff too.

Infilak wrote:

Yes, it's unfortunate to not be able to use the highest refresh rates on our 240 Hz monitors. I hope Apple fixes this sometime soon.

MacOS 15.1 has been released.

Any changes?

Thanks! The ASUS PG32UCDP has a completely different LG WOLED panel, so it seems the issue isn't limited to Samsung QD-OLED panels.

Exactly same issue here. 2 panics already. Mac Studio M4 Max with Dell U4025QW. And this display goes only to 120Hz.

if VPN vendors stuck with doing VPN, using them they would be a modestly bad idea. But most VPN vendors also scan your files for Viruses, often intervening in your Internet activity to break into encrypted connections to be FIRST to scan your files, and leave it less secure to completely broken. VPN for any purpose by institutional network presence is just a bad idea.

If you do not have a recent local, disk-based backup, your computer is like a ticking Time bomb. You are only one disk failure, one crazy software, or one "oops" away from losing EVERYTHING! Drives do not last forever. It is not a question of IF it will fail, only WHEN it will fail. In addition, you never know when crazy software or Pilot Error throws away far more than you intended.

If you are using another direct-to-disk backup method that you prefer, and you currently have a recent disk-based backup, that is great. If not, you should consider using Built-in Time Machine. Take steps to acquire an external drive as soon as possible. If you buy one, a drive 2 to 3 times or larger than your boot drive is preferable for long term trouble-free operation. Do not pay extra for a drive that is fast.  (You can get by for a while with a "found" smaller drive if necessary, but it will eventually become annoying).

Attach your external drive and use

System preferences > Time machine ...

... to turn on Time Machine and specify what drive to store your Backups on.  It may ask to initialize the new drive, and that is as expected. APFS format is default format if running MacOS 11 Big Sur or later.

Time machine works quietly and automatically in the background, without interrupting your regular work, and only saves the incremental changes (after the first full backup). Time machine backs up every connected drive that is in a Mac compatible format. it can not back up Windows format drives.

Time Machine's "claim to fame" is that it is the backup that gets done. It does not ruin performance of the rest of the computer while doing its backup operations. You do not have to set aside a "Special Time" when you only do backups. When you need it, your Time machine Backup is much more likely to be there.

How to use Time Machine to Backup or Restore your Mac:

Back up your Mac with Time Machine - Apple Support

pixelwave wrote:

As I wrote in my post.. that is the version I am on. So no …

The original poster is Infilak.

This is not your discussion thread, you are hijacking it.

You have no posted your etrecheck report, and all manner of things might be happening to your system alone.