Why does my Canon EOS R camera show Err 70 or freeze with a Godox flash/transmitter, and how can I fix it?

Question

I’m using a newer Canon EOS R-series body with the multifunction hot shoe (including the front-edge contacts). Canon says it is backward-compatible with older E-TTL accessories, but when I mount a Godox flash or Godox transmitter, the camera sometimes throws Err 70 or freezes until I power-cycle it.

What causes this with Godox gear, and what are the practical fixes or workarounds?

user27440 · Answer

Hotshoe seating is misaligned

Canon made the new multi-function hotshoe a little deeper than the older traditional hotshoe, so a Godox transmitter or speedlight can sit a little too far forward into the hotshoe for good electrical contact. This can affect all the hotshoe electronic communication (TTL, HSS, etc.).

To fix the seating, you have two options:

Push the flash/tranmsitter all the way into the hotshoe, then partially lock it down, and slowly pull back until you hear a click as the locking pin engages.
Buy an AD-E1 hotshoe adapter and use it.

Speedlight AF-assist miscommunication throws the Err 70

The new hotshoe communication protocol on the R bodies has apparently changed how AF assist functions are communicated and Godox hasn't cracked it yet.

So on the camera body, disable AF assist, set it to use the LED on the camera body. Alternatively, you can also set the AF mode to servo rather than one-shot, which also deactivates AF assist.

See also: Julian Krakow's youtube video on these issues: https://www.youtube.com/watch?v=lgCcv7sGUdQ