I'm trying to build Polkadot as a relay chain for a tutorial but compiling one of its dependencies fails! I may be missing some tools. Could you help? Platform: MacOS (Intel)

Compiling prost-build v0.10.4
error: failed to run custom build command for `prost-build v0.10.4`

Caused by:
  process didn't exit successfully: `<redacted_path>/polkadot/target/release/build/prost-build-c6015cab4894bbe1/build-script-build` (exit status: 101)
  --- stdout
  CMAKE_TOOLCHAIN_FILE_x86_64-apple-darwin = None
  CMAKE_TOOLCHAIN_FILE_x86_64_apple_darwin = None
  CMAKE_GENERATOR_x86_64-apple-darwin = None
  CMAKE_GENERATOR_x86_64_apple_darwin = None
  CMAKE_PREFIX_PATH_x86_64-apple-darwin = None
  CMAKE_PREFIX_PATH_x86_64_apple_darwin = None
  CMAKE_x86_64-apple-darwin = None
  CMAKE_x86_64_apple_darwin = None
  CMAKE = None
  running: "cmake" "<redacted_path>/.cargo/registry/src/github.com-1ecc6299db9ec823/prost-build-0.10.4/third-party/protobuf/cmake" "-Dprotobuf_BUILD_TESTS=OFF" "-DCMAKE_INSTALL_PREFIX=<redacted_path>/polkadot/target/release/build/prost-build-330684d335a6d019/out" "-DCMAKE_C_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64 -arch x86_64" "-DCMAKE_C_COMPILER=/usr/bin/cc" "-DCMAKE_CXX_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64 -arch x86_64" "-DCMAKE_CXX_COMPILER=/usr/bin/c++" "-DCMAKE_ASM_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64 -arch x86_64" "-DCMAKE_ASM_COMPILER=/usr/bin/cc" "-DCMAKE_BUILD_TYPE=Debug"

  --- stderr
  thread 'main' panicked at '
  failed to execute command: No such file or directory (os error 2)
  is `cmake` not installed?

  build script failed, must exit now', <redacted_path>/.cargo/registry/src/github.com-1ecc6299db9ec823/cmake-0.1.48/src/lib.rs:975:5
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: build failed

I have previously built the substrate-node-template project successfully. From the error it looks like I have no cmake installed but I have installed the Apple's developers tools and in general I've used this machine for development, including compiling generic Rust code.

Any clues? Thanks!

  • 1
    Note I've also covered some of the Substrate tutorials prior to the one about starting my own relay chain (and connecting parachains to it) docs.substrate.io/tutorials/connect-other-chains/local-relay
    – stano
    Jul 2, 2022 at 13:46
  • I also updated my rust toolchain to the latest version at time of writing and still no luck - 1.62.0 for stable and 1.64.0-nightly for nightly.
    – stano
    Jul 2, 2022 at 13:55
  • 2
    Hi, can you try install cmake (e.g brew install cmake) and then should works.
    – pepoviola
    Jul 2, 2022 at 14:43
  • Hi @pepoviola thank you for the suggestion! Do you have an idea why that changed in prost-build v0.10.4? I'm currently building the substrate-node-template without any issue and it successfully compiles prost-build v0.9.0. So I try to understand before installing additional tools
    – stano
    Jul 2, 2022 at 14:53
  • To answer my own question - probably this commit in prost-build started requiring cmake - "build: Remove bundled protoc and build from source" github.com/tokio-rs/prost/commit/…
    – stano
    Jul 2, 2022 at 15:00

2 Answers 2


Probably the most frictionless way to fix this is by installing cmake.

Alternatively, provide a pre-built protoc to the build process.

More context about prost:

PROST! a Protocol Buffers implementation for the Rust Language


prost-build makes it easy to generate Rust code from .proto files as part of a Cargo build

To compile prost-build you can either provide cmake or precompiled protoc. Luckily, the prost-build Readme links to the installation instructions of protoc where you can find a pre-build binary for your system.

Using this binary with an environment variable lets cargo build the dependency (prost-build) without having to also build protoc.

PROTOC=/path/to/protoc cargo build --release


This will fix by just installing c-make.

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