Since updating my guix client (but not yet my server) to include the recent commits related to the protocol update, I'm seeing these errors non-deterministically while building things. Retrying usually results in success.
mhw@jojen:~/guix$ guix build -K openssl --cores=1 substitute: updating list of substitutes from 'http://hydra.gnu.org'... 100.0% The following derivation will be built: /gnu/store/5hzf27bgygjp5ah3bfy8m0aa93yazgk3-openssl-1.0.2e.drv guix build: error: build failed: EOF expected (protocol error?) Mark