Remote builders: operation 'addToStore' is not supported by store


After having to run several builds this afternoon on my machine, I finally decided to be serious about setting up remote builders. I’ve setup my nix.buildMachines and for now set nix.distributedBuilds = false; because I want to build on remote builders only when I explicitly decide it. While trying, I triggered an unhelpful error "operation not supported by store ". Luckily, nix master generates better messages, hence I tried the same command with nix master

/nix/store/1w96sgqwv5aabhk68av84h9yhlmnz98q-nix-2.3pre6628_25722bd/bin/nix-build --store ssh://myRemoteBuilder -A python3Packages.pandas ~/nixpkgs                                                                                                       
error: while evaluating the attribute 'args' of the derivation 'python3.7-pandas-0.24.1' at /home/teto/nixpkgs/pkgs/development/interpreters/python/mk-python-derivation.nix:73:3:
operation 'addToStore' is not supported by store 'ssh://myRemoteBuilder'

This is a bit more precise yet I don’t know how to solve this problem.