astral-sh/ruff · error

`uv sync` failed with exit code {:?}: {}

Error message

`uv sync` failed with exit code {:?}:
{}

What it means

Generic failure path of setup_venv: after running `uv sync` to install the mdtest's external dependencies into a temporary venv, the command exited non-zero for any reason not covered by the lockfile checks, so the harness bails with uv's exit code and stderr.

Source

Thrown at crates/ty_test/src/external_dependencies.rs:123

    if !uv_sync_output.status.success() {
        let stderr = String::from_utf8_lossy(&uv_sync_output.stderr);

        if use_locked
            && stderr.contains("`uv.lock` needs to be updated, but `--locked` was provided.")
        {
            bail!(
                "Lockfile is out of date. Use one of these commands to regenerate it:\n\
                 \n\
                 uv run crates/ty_python_semantic/mdtest.py -e external/\n\
                 \n\
                 Or using cargo:\n\
                 \n\
                 MDTEST_EXTERNAL=1 MDTEST_UPGRADE_LOCKFILES=1 cargo test -p ty_python_semantic --test mdtest mdtest__external"
            );
        }

        bail!(
            "`uv sync` failed with exit code {:?}:\n{}",
            uv_sync_output.status.code(),
            stderr
        );
    }

    // In upgrade mode, copy the generated lockfile back to the source location
    if upgrade_lockfile {
        let temp_lockfile = temp_path.join("uv.lock");
        let temp_lockfile = temp_lockfile.as_std_path();
        if temp_lockfile.exists() {
            std::fs::copy(temp_lockfile, lockfile_path)
                .with_context(|| format!("Failed to write lockfile to '{lockfile_path}'"))?;
        } else {
            bail!(
                "Expected uv to create a lockfile at '{}'",
                temp_lockfile.display()
            );

View on GitHub (pinned to 26f38c119c)

Solutions

1. Read the stderr included in the message to identify uv's actual complaint
2. Check network/proxy access to the package index and retry
3. Fix unresolvable/conflicting dependency specs in the mdtest's external-dependencies declaration
4. Ensure a suitable `uv` is installed and on PATH (`uv --version`) and that a matching Python interpreter is available

Example fix

// diagnose
bash -c 'MDTEST_EXTERNAL=1 cargo test -p ty_python_semantic --test mdtest mdtest__external 2>&1 | tail -40'
// after fixing the underlying cause (e.g. corrected dependency spec)
---
external_dependencies:
  dependencies:
    - numpy==2.1.0   # was: numpy  (unpinned caused resolution failure)
---

uv --version && uv python find  # confirm uv and a suitable interpreter exist

let output = std::process::Command::new("uv").args(["sync", "--locked"]).output()?;
if !output.status.success() {
    eprintln!("uv sync failed ({}): {}",
        output.status.code().unwrap_or(-1),
        String::from_utf8_lossy(&output.stderr));
}

When it happens

Trigger: `uv sync` fails inside setup_venv (crates/ty_test/src/external_dependencies.rs:123) due to network errors during dependency download, an unresolvable requirement set, a Python version mismatch with the venv, or uv not finding a valid interpreter.

Common situations: Working offline or behind a proxy that blocks PyPI; a dependency spec in the mdtest that cannot be resolved; an incompatible `requires-python` in the project; a broken or too-old `uv` on PATH.

Related errors

• For an mdtest with external dependencies, a Python platform
• Lockfile not found at '{lockfile_path}'. Run with `MDTEST_UP
• Lockfile is out of date. Use one of these commands to regene
• Could not find mdtest executable after successful compilatio
• Expected uv to create a lockfile at '{}'

AI-assisted analysis of astral-sh/ruff@26f38c119c (2026-09-05). Data as JSON: /api/errors/466a71b323283641. Report an issue: GitHub.