Diagnostic query: Unexpected kernel panic on macOS Sequoia 15.1 after waking (1794482915)

[Liam O’Connor]

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?

[Sarah Mitchell]

The AppleThunderboltNHI assertion often maps to a Thunderbolt/USB-C controller firmware mismatch exacerbated by the 15.1 IOThunderboltFamily kext update; verify the active controller firmware version via system_profiler SPThunderboltDataType | grep -i firmware and cross-reference against Apple’s ThunderboltFirmwareUpdater manifest for your SMBIOS. If the dock presents a downstream USB4/DP alt-mode device, force a cold re-enumeration by disconnecting AC power from the dock, holding the Mac’s power button for 10s (SMC reset), then reattaching only the host cable before applying dock power. As a diagnostic control, boot into macOS Recovery (⌘R) and run ioreg -l -p IODeviceTree | grep -e AppleThunderboltNHI -e "AAPL,current-power-state" to confirm the NHI driver attaches cleanly without third-party IOKit personalities loaded.

iPhone 16 Pro (256GB, iOS 26) | iPad Air M2

Austin, TX | "Always try Finder Update before touching Restore."

[Ethan Carter]

Background photolibraryd metadata reconciliation can spike kernel_task CPU during wake, starving the IOPlatformPluginFamily thermal budget and triggering the watchdog panic; correlate log show --predicate 'subsystem == "com.apple.photos"' --last 1h | grep -i wake against the panic timestamp. Disable “Optimize Mac Storage” in Photos > Settings > iCloud temporarily and purge local caches via sudo rm -rf ~/Library/Caches/com.apple.photos* to eliminate APFS snapshot I/O contention on the system volume. Concurrently, a flaky Bluetooth HID proxy (common with Magic Keyboard/Trackpad) can assert AppleThunderboltNHI via the shared IOPCIDevice interrupt line; test with sudo pkill bluetoothd && sudo nvram bluetoothHostControllerSwitchBehavior=never to force USB-only transport.

iPhone 16 Pro Max | AirPods Max USB-C

San Diego, CA | "Turn off Low Power Mode when debugging iCloud Photos stalls."

[Emily Hart]

An authenticated Apple Watch unlock handshake (com.apple.authd → kernel via IOUserClient) can deadlock the IOPlatformPluginFamily power-state machine if the Secure Enclave Processor (SEP) firmware is stale; verify SEP version with system_profiler SPiBridgeDataType | grep -i "firmware version" and ensure it matches the 15.1 BridgeOS build (19P549). If you use Universal Control/Stage Manager with a paired iPad, the Continuity framework spawns a virtual display IOFramebuffer that shares the Thunderbolt NHI’s DMA engine—disable “Allow Handoff” and “Cursor and Keyboard” in System Settings > General > AirPlay & Handoff to isolate the display path. Finally, a degraded battery (system_profiler SPPowerDataType | grep -i "condition|cycle count") reporting erroneous MaxCapacity can cause the SMC to request an invalid P-state transition on wake; if Cycle Count > 1000 or Condition != Normal, schedule a battery replacement before further kernel debugging.

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

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

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