New Phoenix app fails on first deploy: ERROR [internal] load build context

I assume this has to do with Elixir/Erlang versions? Is there an approved list of pairs?

fly deploy
==> Verifying app config
Validating /Users/bryan/thrive/app/fly.toml
Platform: machines
✓ Configuration is valid
--> Verified app config
==> Building image
Remote builder fly-builder-misty-snowflake-7311 ready
==> Building image with Docker
--> docker host: 20.10.12 linux x86_64
[+] Building 17.4s (12/28)                                                                                                                                                                                                                                                                                            
 => [internal] load build definition from Dockerfile                                                                                                                                                                                                                                                             0.2s
 => => transferring dockerfile: 69B                                                                                                                                                                                                                                                                              0.2s
 => [internal] load .dockerignore                                                                                                                                                                                                                                                                                0.2s
 => => transferring context: 72B                                                                                                                                                                                                                                                                                 0.2s
 => [internal] load metadata for docker.io/library/debian:bullseye-20220801-slim                                                                                                                                                                                                                                 0.5s
 => [internal] load metadata for docker.io/hexpm/elixir:1.14.3-erlang-25.1.1-debian-bullseye-20220801-slim                                                                                                                                                                                                       0.6s
 => CACHED [builder  1/17] FROM docker.io/hexpm/elixir:1.14.3-erlang-25.1.1-debian-bullseye-20220801-slim@sha256:d87ac6920be4a8bfd39dab17172231fd0d2552a83f4036a80fcd93b59771a924                                                                                                                                0.0s
 => ERROR [internal] load build context                                                                                                                                                                                                                                                                         14.1s
 => => transferring context: 331.39kB                                                                                                                                                                                                                                                                           14.1s
 => [stage-1 1/6] FROM docker.io/library/debian:bullseye-20220801-slim@sha256:a811e62769a642241b168ac34f615fb02da863307a14c4432cea8e5a0f9782b8                                                                                                                                                                   0.0s
 => CACHED [stage-1 2/6] RUN apt-get update -y &&   apt-get install -y libstdc++6 openssl libncurses5 locales ca-certificates   && apt-get clean && rm -f /var/lib/apt/lists/*_*                                                                                                                                 0.0s
 => CACHED [stage-1 3/6] RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && locale-gen                                                                                                                                                                                                                        0.0s
 => CACHED [stage-1 4/6] WORKDIR /app                                                                                                                                                                                                                                                                            0.0s
 => CACHED [stage-1 5/6] RUN chown nobody /app                                                                                                                                                                                                                                                                   0.0s
 => CANCELED [builder  2/17] RUN apt-get update -y && apt-get install -y build-essential git     && apt-get clean && rm -f /var/lib/apt/lists/*_*                                                                                                                                                               14.4s
------                                                                                                                                                                                                                                                                                                                
 > [internal] load build context:                                                                                                                                                                                                                                                                                     
------                                                                                                                                                                                                                                                                                                                
Error: failed to fetch an image or build from source: error building: failed to solve: rpc error: code = Canceled desc = grpc: the client connection is closing   

It had been awhile since I did my last deploy, so I ended up killing the remote worker and when a new one came online the build worked just fine.