Apple Watch keeps restarting: kernel panic "AppleHIDTransportProtocolSCMMailbox invalid checksum"
My Apple Watch has restarted on its own ever since I bought it, roughly every 4-5 hours. It's intermittent, with no obvious trigger. I pulled the crash logs, and all of them show the same kernel panic. Is anyone else seeing this exact error?
Device: Apple Watch (model identifier Watch7,18; Series 11), paired with an iPhone on iOS 27
The panic, identical in every log:
[AppleHIDTransportProtocolSCMMailbox::parseNewReadBytes] Invalid message read from the FIFO ID 1, interface ID 4, report ID 0x52, transfer ID 0xF2: invalid checksum (read: 0xD28F9CF1, calculated: 0xD2901CF1)
What I've seen so far:
- 3 panics in about 13 hours
- 2 on watchOS 26.6, while the watch was erased and sitting on the Setup screen, with no apps or data on it
- 1 on watchOS 27.0.1 after updating, in normal paired use
- Each one about 20-26 seconds after the watch woke from sleep
- The last driver loaded before every panic was AppleMultitouchDriver (the touchscreen driver)
- Memory pressure was false in all of them, and a watchdog reset follows each panic
What I've already tried:
- Unpaired and erased the watch, then set it up again
- Updated to watchOS 27.0.1 (the version that fixed the Series 12 / Ultra 4 reboot bug; this is a different panic)
- Two visits to an authorised service centre; the case is now escalated with Apple Support
- Filed in Feedback Assistant as ***
Questions:
- Has anyone else seen "AppleHIDTransportProtocolSCMMailbox" or "invalid checksum" in their watch panic logs?
- If so, which model and watchOS version, and did Apple repair or replace the watch?
How to check your own logs: on the iPhone, go to Settings > Privacy & Security > Analytics & Improvements > Analytics Data and look for files starting with "panic-full". Open one and search for "HIDTransport".
[Edited by Moderator]
Apple Watch Series 11