Build fails: protoc failed: bitswap.v1.2.0.proto: No such file or directory

Question

When building a Substrate-project, I receive the following error: protoc failed: bitswap.v1.2.0.proto: No such file or directory

Answer 1

Most likely your protobuf-compiler version is outdated.

Starting from Substrate dependency version polkadot-v0.9.32, the protobuf-compiler version supplied by the apt repository on Ubuntu 18 or older does not meet the version requirement to build a Substrate project. This can also happen with package managers used by other operating systems.

To resolve on Ubuntu 18 or older:

1. Remove protobuf-compiler: sudo apt remove protobuf-compiler
2. Use temporary folder: tmp_folder="/tmp/proto-$RANDOM" && mkdir -p "$tmp_folder" && pushd "$tmp_folder" > /dev/null
3. Download a recent version of Protobuf from the official repository (the following version was tested): wget https://github.com/protocolbuffers/protobuf/releases/download/v23.3/protoc-23.3-linux-x86_64.zip
4. Unpack protoc from zip file: unzip protoc-23.3-linux-x86_64.zip bin/protoc
5. Move protoc into binary folder: sudo cp -r ./bin/ /usr
6. Move back to starting point: popd > /dev/null
7. (Optional when using /tmp) Clean up: rm -r "$tmp_folder"
8. Verify that protobuf-compiler was installed and can be located: protoc --version (should emit "libprotoc 23.3" in this case)

All-in-one command:

sudo apt remove protobuf-compiler \
  && tmp_folder="/tmp/proto-$RANDOM" \
  && mkdir -p "$tmp_folder" \
  && pushd "$tmp_folder" > /dev/null \
  && wget https://github.com/protocolbuffers/protobuf/releases/download/v23.3/protoc-23.3-linux-x86_64.zip \
  && unzip protoc-23.3-linux-x86_64.zip bin/protoc \
  && sudo cp -r ./bin/ /usr \
  && popd > /dev/null \
  && rm -r "$tmp_folder" \
  && protoc --version