PyO3/pyo3 · error

Neither abi3 or abi3t features are enabled

Error message

Neither abi3 or abi3t features are enabled

What it means

pyo3's build config requires one of the `abi3` or `abi3t` (free-threaded stable ABI) cargo features to be enabled when a stable-ABI configuration is being derived. `default_stable_abi_config` is only reached when the build expects a stable ABI target, and finding neither feature enabled means the stable ABI request is inconsistent with the declared features, so the build fails immediately with this message.

Solutions

1. Add `abi3` (or `abi3t` for free-threaded Python) to the pyo3 feature list in Cargo.toml
2. If you do not want the stable ABI, remove whatever invokes the abi3 configuration path (e.g. abi3-pyXY features or PYO3 abi3-related env settings)
3. Run `cargo tree -e features` to confirm the abi3 feature actually reaches pyo3, since features are unified across the dependency graph

Example fix

// before
pyo3 = { version = "0.22", features = ["extension-module"] }
// after
pyo3 = { version = "0.22", features = ["extension-module", "abi3-py38"] }

# Cargo.toml check before building
// shell
 cargo tree -e features | grep -q 'pyo3 .*abi3' || echo 'abi3 feature missing: add features = ["abi3"] to pyo3'

When it happens

Trigger: Enabling stable-ABI-related configuration (e.g. PYO3_USE_ABI3_FORWARD_COMPATIBILITY paths, cross-compilation config files, or pyo3-build-config internals that call default_stable_abi_config) without enabling the `abi3` or `abi3t` cargo feature on the pyo3 dependency.

Common situations: Developers toggle `features = ["abi3"]` off while leaving other abi3 settings in place; Cargo feature resolution strips `abi3` because another crate in the graph disabled it; hand-written build scripts or config-generation code call into pyo3-build-config expecting a stable ABI but never declare the feature.

Related errors

• cannot set a minimum Python version
• Cannot target an abi3t version below
• Invalid config that sets both target_abi and abi3.
• At least GraalPy version
• broken Python interpreter

AI-assisted analysis of PyO3/pyo3@ac9b6899d3 (2026-09-05). Data as JSON: /api/errors/43b0750167451373. Report an issue: GitHub.

Appendix: source

Thrown at pyo3-build-config/src/impl_.rs:2323

}

/// Generates "default" interpreter configuration when compiling stable ABI extensions
/// without a working Python interpreter.
///
/// `abi3_version` or `abi3t_version` specifies the minimum supported Stable ABI
/// CPython version and which stable ABI to target.
///
/// This should work for most CPython extension modules when compiling on
/// Windows, macOS and Linux.
///
/// Must be called from a PyO3 crate build script.
fn default_stable_abi_config(
    host: &Triple,
    abi3_version: Option<PythonVersion>,
    abi3t_version: Option<PythonVersion>,
) -> Result<InterpreterConfig> {
    if abi3_version.is_none() && abi3t_version.is_none() {
        bail!("Neither abi3 or abi3t features are enabled")
    }
    let (stable_abi, version) = if let Some(version) = abi3_version {
        (StableAbi::Abi3, version)
    } else if let Some(version) = abi3t_version {
        (StableAbi::Abi3t, version)
    } else {
        unreachable!();
    };

    if stable_abi == StableAbi::Abi3t && version < MINIMUM_SUPPORTED_VERSION_ABI3T {
        bail!("Cannot target an abi3t version below {MINIMUM_SUPPORTED_VERSION_ABI3T}")
    }

    // FIXME: PyPy & GraalPy do not support the Stable ABI.
    let target_abi = PythonAbiBuilder::new(PythonImplementation::CPython, version)
        .stable_abi(stable_abi)
        .finalize()?;
    let builder = InterpreterConfigBuilder::new(PythonImplementation::CPython, version)

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