SB_0000005 I2C Storm can cause inflight reboots, Chibios ONLY, not Nuttx (all cube and Pixhawk hardware, including clones and derivatives)


Update ALL CHIBIOS Copter USERS MUST USE 3.6.12 or cease flight.

Critical Safety Update is in Copter 3.6.12
Update Friday, 13th December. This is a Chibios only issue. Old hardware running old custom or stock Nuttx firmware is not affected by this SB

Due to an issue with a bug in the I2C system for ArduCopter for 3.6.10 version and earlier and Arduplane before 4.0

Please ground any vehicles that have not BEEN updated to Arduplane 4.0 or 3.6.11 for Arducopter or later.

This issue has lead to aircraft failing mid flight, and the details can be found in the Ardupilot release notes for 3.6.11

A rare case can still occur in 3.6.11, 3.6.12 will be released shortly, and as soon as it is, this notice will be updated.


Hey @philip
What if I’m not using the I2C at all? I have here2 on CAN and GPS2 without mag.

The bug is a very serious one, please upgrade immediately regardless

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Have I understood correctly that I2C is not fully safe on 3.6.11 if I2C bus gets noisy (EMI).
This was a “belt and braces” fix according to Tridge and was done on the following commit which recently merged to master. Maybe the fix is in 3.6.12-rc1?


Belt and braces is a term that indicates that all options of failure are covered…

You can hold your pants up with a belt…
You can hold your pants up with braces…

Belt and braces offers redundancy…

This PR is the additional protection in case of hardware failure that was found in another brand or autopilot.

@philip Thanks for all the updates.

Just to be sure, is that SB also affecting PH2 running with older NuttX bootloader?
I am running 3.9.2 on some planes and 3.6.6 on copters, both with NuttX bootloader.

Thank you,

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We are investigating if Nuttx is affected, and will update the SB as we gather evidence

We would prefer due to SB02…

ALL copters should be on 3.6.11 minimum, and updating to 3.6.12 ASAP.

All planes should be on latest 4.0.x

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hi @philip.

I have an onflight reboot crash, there is any way to check with the log if that crash is related with this?


Please post it over on the ardupilot forum and ask there. I believe that the next log will be the one that shows the issue

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Here is the link to the question, in case you want to give it a look.

Please remove the term “Storm” from this.

It’s a slang term we used when investigating/working it (like “the onion”) but is misleading for public announcements. I just got a message from a concerned user asking if they need to worry about this or not if they don’t plan to fly in bad weather.

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That term is used in the release notes.

An “interrupt storm” is a Normal industry term to describe this issue.

Feel free to discuss this matter with Tridge et al

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I’m already running AC 3.6.11 on CUAV v5+ board. It’s mandatory to update AC 3.6.12 to avoid I2C Strom reboot issue… I

Hi Philip, which firmware should I install in a Cube Black? Apparently V.4.0.3 has some issues. Should I use a previous version or 4.0.4? Thanks

What issues?

4.04 is my favourite

Hi Alex and Philip,
Could you please send me the link to install V.4.0.3 or V4.0.4 on Black cube as I am not able to find it on the internet?

Thanks in advance.

Standard release on mission planner