Frequent Kernel Panics with Thunderbolt Display: iomfb_driver and Iomfb mailbox

Hi Colin,

I received my Dell UltraSharp U4025QW just 10 days ago. Every day, I have at least one (up to 3) panic crashes with my MacBook Pro 16" Apple M2 Max 64GB, running macOS Sonoma 14.5.

From the panic logs located in /Library/Logs/DiagnosticReports, I can also find iomfb_driver and Iomfb_mailbox.

Reading your post, I have a few questions:

• When you say VRR, you do mean Variable Refresh Rate; correct?
• So, you set the Refresh Rate to 120 Hertz. Accordingly, it stopped crashing?
• What about the High Dynamic Range? ON or OFF?

For the other readers, you find this setting in SYSTEM SETTINGS → DISPLAYS → DELL U4025QW.

Be aware that if you control your resolution with Dell Display and Peripheral Manager (DDPM), the software automatically set the refresh rate to Variable. So, the kernel panics will occur again.

After three days, I can confirm that this setting works perfectly fine.

• Refresh Rate = 120 Hz
• HDR = ON

When new panics occur, I will let you know.

Thank you for the prompt reply, Colin. I was about to return my display, due to the poor response from Dell customer service. One cannot image what kind of nonsense they communicate.

I'll test this setting out for the next-coming days:

• Refresh Rate = 120 Hz
• HDR = ON

I'll let post here whether it is stable.

Thanks for your posts. Same problem here, MBP 16 M2 Max 64GB 30GPU cores, had 3 kernal panics today (first day of using the Ultrasharp). Now changed the cable and fixed the framrate to 60. If I don't post an update here, that will have solved the problem. Dell support suggested to connect a different computer.

Thanks for the addition. I am not using DDPM. I am convinced that this should all be done by the OS.