Diagnostic query: Unexpected kernel panic on macOS Sequoia 15.1 after waking (1794679675)

[Hannah Brooks]

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?

[Emily Hart]

The AppleThunderboltNHI assertion during wake often correlates with spurious power-change interrupts from the embedded controller when a paired Apple Watch attempts proximity unlock while the TBT controller is still initializing; unpair the Watch in System Settings → Bluetooth and test a full sleep/wake cycle without it present. Verify the EC’s reported battery health and cycle count via ioreg -r -c AppleSmartBattery | grep -E '"CycleCount"|"DesignCapacity"|"MaxCapacity"' — a degraded pack can cause voltage sag on wake that trips the NHI’s power-state machine. If you use Universal Control/Stage Manager with an iPad on the same iCloud account, disable Settings → General → AirPlay & Handoff → Cursor and Keyboard on the iPad; the continuity daemon (com.apple.continuity) has been observed hammering the TBT path during dark wake. As a hardware recovery step, disconnect all TBT/USB-C devices, hold Touch ID + Control + Option + Shift for 7 s to force an SMC/EC hard reset, then cold-boot with only the power adapter attached.

iPad Pro 13″ M4 | Apple Watch Ultra 2 | iPhone 15 Pro

Toronto, ON | "Battery cycle count beats random percentage guesses."

[Rachel Kim]

A runaway WindowServer or Safari Web Content process pinned to a P-core during dark wake can starve the IOPlatformPluginFamily thermal policy thread, triggering the NHI watchdog; capture a 30 s spindump at wake with sudo spindump -reveal -noProcessingWhileSampling 30 and search for kIOPlatformPluginThermal or AppleThunderboltNHI backtraces. Audit login items and launch agents via launchctl list | grep -v com.apple and osascript -e 'tell application "System Events" to get the name of every login item' — third-party menu-bar utilities (e.g., display managers, dock helpers) frequently inject IOKit callbacks that deadlock the TBT hot-plug path on resume. Temporarily quarantine Safari’s saved state (~/Library/Saved Application State/com.apple.Safari.savedState) and disable Safari → Settings → Advanced → Show features for web developers → Experimental Features → WebGPU to rule out a WebKit GPU process crash leaking IOSurface references across sleep. If the panic persists, boot with nvram boot-args="io=0x1000" to force single-user I/O diagnostics and confirm whether the NHI assertion originates from user-space or the kernel’s AppleThunderboltNHIType3 driver.

MacBook Pro 14″ M4 (32GB) | iPhone 15

Vancouver, BC | "Read crash logs bottom-up from the faulting thread."

[Owen Parker]

Check the Unified Log for liquid or corrosion events via log show --predicate 'eventMessage CONTAINS[c] "liquid" OR eventMessage CONTAINS[c] "corrosion"' --last 7d — a false-positive liquid-detection flag on the TBT/USB-C port controller will assert AppleThunderboltNHI during the wake sequence as the SMC gates power to the PHY. If the Mac has an eSIM modem (cellular models), reset the baseband with sudo /usr/libexec/PlistBuddy -c "Delete :DeviceSettings" /Library/Preferences/com.apple.modem.plist 2>/dev/null; sudo pkill -HUP com.apple.CommCenter and disable System Settings → Network → Cellular → Allow Cellular Data Switching to prevent a modem firmware hang from stalling the PCIe link shared with the NHI. Thermally, verify the VRM and TBT retimer temps via sudo powermetrics --samplers smc -i 1000 -n 1 | grep -iE 'tbt|vrm|thunderbolt' immediately after wake; sustained >95 °C on the retimer triggers an emergency NHI reset that manifests as the observed panic. As a definitive isolation, run Apple Diagnostics (D at boot) with the dock disconnected — any PPT or NHT reference codes confirm a firmware/hardware fault in the TBT controller’s power-gating sequence rather than an APFS snapshot bottleneck.

iPhone 14 Pro | Apple Watch Series 10 | MagSafe Duo

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

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