astral-sh/uv · error · anyhow::Error

pip-compile's `--config` is unsupported (uv does not use a c

Error message

pip-compile's `--config` is unsupported (uv does not use a configuration file)

What it means

pip-compile's `--config PATH` points at a pip.conf-style configuration file. uv's pip interface does not read pip configuration files at all — its settings come from CLI flags, environment variables, and `uv.toml`/`pyproject.toml` — so `PipCompileCompatArgs::validate()` rejects the flag rather than ignoring a file you expect to be honored. The pip-sync variant fails the same way (compat.rs:237).

Source

Thrown at crates/uv-cli/src/compat.rs:129

            return Err(anyhow!(
                "pip-compile's `--client-cert` is unsupported (uv doesn't support dedicated client certificates)"
            ));
        }

        if self.emit_trusted_host {
            return Err(anyhow!(
                "pip-compile's `--emit-trusted-host` is unsupported"
            ));
        }

        if self.no_emit_trusted_host {
            warn_user!(
                "pip-compile's `--no-emit-trusted-host` has no effect (uv never emits trusted hosts)"
            );
        }

        if self.config.is_some() {
            return Err(anyhow!(
                "pip-compile's `--config` is unsupported (uv does not use a configuration file)"
            ));
        }

        if self.emit_options {
            return Err(anyhow!(
                "pip-compile's `--emit-options` is unsupported (try `--emit-build-options` instead)"
            ));
        }

        if self.no_emit_options {
            warn_user!("pip-compile's `--no-emit-options` has no effect (uv never emits options)");
        }

        if self.pip_args.is_some() {
            return Err(anyhow!(
                "pip-compile's `--pip-args` is unsupported (try passing arguments to uv directly)"
            ));

View on GitHub (pinned to f1a42680ff)

Solutions

1. Remove `--config` and move the settings into `uv.toml` (or `[tool.uv]`/`[tool.uv.pip]` in pyproject.toml) next to the requirements file.
2. Translate remaining options to CLI flags or `UV_*` environment variables in the script.
3. Use `--isolated`-style explicitness: keep all uv pip settings in version control so no ambient config is needed.

Example fix

# before
uv pip compile --config pip-tools.conf requirements.in

# after (uv.toml)
# [[pip.index]]
# url = "https://pypi.internal/simple"
uv pip compile requirements.in

def assert_no_pip_config(argv: list[str]) -> None:
    if any(a == "--config" or a.startswith("--config=") for a in argv):
        raise ValueError("uv does not read pip config files; move settings to uv.toml or flags")

When it happens

Trigger: `uv pip compile --config pip.conf requirements.in` or `uv pip sync --config pip.conf requirements.txt` after migrating a pipeline that kept per-project pip configuration in a file.

Common situations: Monorepos with per-directory pip.conf; CI that parameterized pip-compile with a generated config file; teams assuming uv reads pip.conf because the subcommands are pip-compatible.

Related errors

• pip-compile's `--reuse-hashes` is unsupported (uv doesn't re
• pip-compile's `--resolver=legacy` is unsupported (uv always
• pip-compile's `--max-rounds` is unsupported (uv always resol
• pip-compile's `--client-cert` is unsupported (uv doesn't sup
• pip-compile's `--emit-trusted-host` is unsupported

AI-assisted analysis of astral-sh/uv@f1a42680ff (2026-08-16). Data as JSON: /api/errors/fc43690215ff5e72. Report an issue: GitHub.