Migrating from scikit-build


scikit-build-core is under active development. This guidance will be updated on a best-effort basis, but if you are working at the bleeding edge some of it may be out of date.

Config changes

  • The build-system.build-backend key in pyproject.toml must be changed to scikit_build_core.build.

  • Replace scikit-build with scikit-build-core in build-system.requires.

  • You should remove cmake and ninja from build-system.requires. scikit-build-core will add these if necessary, but will respect existing installations of the tools by default, which allows compatibility with systems where binaries are not available on PyPI but can be installed from elsewhere. Instead, set the minimum required versions in the [tool.scikit-build] table: cmake.minimum-version and ninja.minimum-version.

  • You must fill out the tool.scikit-build table in pyproject.toml, see getting started for more information.

  • If your project is primarily configured using setup.py or setup.cfg, you will need to move the configuration to pyproject.toml. The project metadata spec shows the information that can be placed directly in the project table. For additional metadata, see our configuration guide. A useful trick for performing this migration is to change the build-backend from skbuild to setuptools, install hatch, and run hatch new --init. This should automatically migrate the configuration to pyproject.toml, after which you can change the build-backend to scikit-build-core.

  • If you specify files to include in sdists via MANIFEST.in, with scikit-build-core you should now instead use the sdist.include and sdist.exclude fields in the tool.scikit-build table. Note that scikit-build-core uses all non .gitignore’d files by default, so this is often minimal or not needed.

CMake changes

scikit-build users wishing to switch to scikit-build-core should be aware of the following changes that must be made to their CMake files:

  • The PythonExtensions CMake module distributed with scikit-build is not part of scikit-build-core. Due to improvements in CMake’s built-in support for building Python extension modules, most of this module is no longer necessary. Change

find_package(PythonExtensions REQUIRED)
add_library(${LIBRARY} MODULE ${FILENAME})


find_package(Python COMPONENTS Interpreter Development.Module REQUIRED)
python_add_library(${LIBRARY} MODULE WITH_SOABI ${FILENAME})
  • The UseCython CMake module distributed with scikit-build is not currently supported. For examples on how to use Cython, see our getting started guide for now.

  • The SKBUILD_CONFIGURE_OPTIONS environment variable is now named SKBUILD_CMAKE_ARGS for consistency.

  • The SKBUILD_BUILD_OPTIONS environment variable is not supported. Some specific features are accessible using alternative variables. In particular, use CMAKE_BUILD_PARALLEL_LEVEL or SKBUILD_CMAKE_VERBOSE to control build parallelism or CMake verbosity directly.