Diagnostic query: Unexpected kernel panic on macOS Sequoia 15.1 after waking (1794718826)

[Rachel Kim]

Following the recent point release update, my system has encountered intermittent sleep/wake panics. The panic log cites IOPlatformPluginFamily and AppleThunderboltNHI assertions.

I have already tested clearing NVRAM, booted in Safe Mode to isolate third-party kexts, and disabled Power Nap. Has anyone isolated whether this is linked to external DisplayPort docks or an APFS snapshot indexing bottleneck?

[Owen Parker]

If the panic correlates with a specific dock port, check log show --predicate 'subsystem == "com.apple.iokit.IOThunderboltFamily"' --last 1h | grep -i "liquid|corrosion|overtemp"; the NHI controller exposes a dedicated ADC channel for port thermals/liquid detection that can falsely assert kIOThunderboltPortStatusFault during wake if the dock’s PD controller leaks VBUS onto CC lines. Verify the dock’s E-Marker cable integrity with ioreg -r -c AppleThunderboltNHI | grep -i "port.*status"—a 0x8000 bitmask indicates a hardware fault condition suppressing the wake vector. If present, isolate by testing a passive TBT3 cable (no active retimer) to rule out the dock’s retimer firmware.

iPhone 14 Pro | Apple Watch Series 10 | MagSafe Duo

Denver, CO | "Let humid USB-C ports air dry — never reach for rice."

[Claire Bennett]

The AppleThunderboltNHI panic often masks a PD contract renegotiation race where the dock’s 100W PDO collapses during wake, causing the Mac’s ApplePMU to assert kIOPMPowerStateChangeFailed (logged as Error 4013-adjacent in UnifiedLog). Capture the USB-PD negotiation trace via sudo powermetrics --show-process-energy -n 1 -i 1000 | grep -A 10 "Thunderbolt" immediately after wake; look for PDO Reject or Hard Reset events. If the dock negotiates 20V/5A but the Mac requests 15V/3A (common on CalDigit/OWC docks with older NVM), the NHI watchdog fires. Fix: Update dock NVM via vendor Windows tool, or force 15V cap via sudo nvram boot-args="tbpd_max_voltage=15000" (requires SIP off).

MacBook Pro 16″ M2 Max | iPhone 16 Plus

London, UK | "Swap the USB-C cable before blaming the logic board."

[Liam O’Connor]

Irrelevant to the NHI panic, but if you run Audio over Thunderbolt (e.g., Universal Audio Apollo, Focusrite RedNet), a stale AppleThunderboltAudio kext (v4.x vs required 5.0+ for Sequoia) can deadlock the IOAudioEngine during powerStateWillChangeTo, manifesting as an IOPlatformPluginFamily timeout. Check kextstat | grep -i thunderboltaudio; if loaded, unload via sudo kextunload -b com.apple.driver.AppleThunderboltAudio and test wake stability. This path shares the NHI mailbox doorbell registers; a stuck audio DMA engine blocks the NHI firmware’s wake ACK, triggering the exact assertion you see.

iMac 24″ M3 (16GB) | HomePod mini Stereo Pair

Dublin, IE | "Clean Wi-Fi multicast fixes half of AirPlay drops."

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