Interesting! Thanks for posting! I haven't seen this particular error, but someone may have!
Do you mind sending your full "deployment log"? You can also ratchet up the logging verbosity by going to Tools -> Global Options -> Publishing -> Show diagnostic information when publishing in the IDE. One last way to increase verbosity even more is by setting:
options(rsconnect.http.verbose = TRUE)
Sharing this information will help us get a sense for where / why the error is being thrown. The other piece that might be helpful is sharing the output of devtools::session_info() after a deployment fails, so we can see what package versions you are using.
I take it this deployment has failed multiple times? The easiest one to debug is the "hello world," since we can know that there is no subtle issue going on in your code.