Thanks Amy for your response.
The server version is indicated by the Docker Git repo version a272b0d, so that should be 4.10.0.
I have not performed any update or upgrade, and none of the upgrade instructions apply to my case.
I wonder if this is related to caching and whether I just need to clean up something, and it’ll work again? Like I said, I do not remember changing anything in between, when suddenly this error showed up.