bytes_retransmit is the number of bytes that had to be send twice because for whatever reason a command had to be retransmitted from the host to the MCU.
Usually this indicates some sort of bandwidth issue, because the host decided to send a command again as it did not receive an acknowledgement in a timely manner.
In itself, it might not be severe unless followed up by “real” errors.
Timeout with MCU / Lost communication with MCU occurs when the host does no longer receive data from the MCU. It can be the wiring or something made the MCU crash (e.g. due to some faulty hardware), so it just no longer reacts.
Unfortunately there is no deeper indication as to what could be the reason
Side notes:
- Happy Hare does currently seem not to play well with Klipper
- From the crash dumps it seems that Klipper was doing nothing else than “playing Neopixel” using 3rd party extras that do not belong to Klipper main-line and as such are not supported nor guaranteed to be free of side-effects, especially if various such 3rd party extras are stacked.