`uv sync` failed to run with exit code

Error message

`uv sync` failed to run with exit code `{code}`, stderr: {stderr}

What it means

The `ty_completion_bench` tool runs `uv sync` in the discovered project directory to provision the `.venv` used for completion benchmarking. If the subprocess exits with a non-zero status, the tool aborts with this error, embedding the exit code and the subprocess's stderr. It means the target project's environment could not be synced, not a bug in ty itself.

Solutions

Run `uv sync` manually in the project directory and fix the underlying resolution or network error it reports
Check the stderr portion of the message for the failing package or index and correct `pyproject.toml`/`uv.lock` accordingly
Verify `uv` is installed and up to date (`uv self update` or reinstall)
Regenerate the lockfile with `uv lock` if it is stale or conflicted
If offline, ensure all dependencies are cached or use `--offline` with a warm cache

Example fix

// before
# pyproject.toml
[project]
dependencies = ["torch==99.0.0"]  # nonexistent version
// after
[project]
dependencies = ["torch>=2.0"]
# then: uv sync

Defensive patterns

Strategy: validation

Validate before calling

# before invoking the tool
uv sync --check || { uv sync; }  # ensure the project env resolves
# or in shell: test -x "$(command -v uv)" && uv lock --check

Try / catch

match ty_completion_bench::run(args) {
    Err(e) if e.to_string().contains("`uv sync` failed") => {
        eprintln!("fix project env: {e}");
        std::process::ExitCode::from(1)
    }
    other => other,
}

Prevention

Commit a valid uv.lock and keep dependencies resolvable
Run `uv sync` once before benchmarking so failures surface early
Check network/proxy access to your package index before running offline-sensitive tools

When it happens

Trigger: Running `ty_completion_bench <file> <offset>` when `uv sync` in the file's containing project fails: invalid or unresolvable `pyproject.toml` dependencies, no network access to package indexes, a missing or broken `uv` installation, lockfile conflicts, or Python interpreter discovery failures.

Common situations: Benchmarking in a project with an unpinned private dependency that is unreachable offline; a stale or corrupted `uv.lock`; running inside a sandbox without internet; `VIRTUAL_ENV` pointing somewhere unusual while the project requires a fresh sync; typo'd requirement specifiers in `pyproject.toml`.

Related errors

AI-assisted analysis of astral-sh/ruff@5bb508f594 (2026-09-05). Data as JSON: /api/errors/a85156203ebab674. Report an issue: GitHub.

Appendix: source

Thrown at crates/ty_completion_bench/src/main.rs:88

        format!(
            "failed to convert file offset `{}` to 32-bit integer",
            args.offset
        )
    })?;

    let uv_sync_output = std::process::Command::new("uv")
        .arg("sync")
        .current_dir(&project_dir)
        .output()
        .with_context(|| format!("failed to run `uv sync` in `{project_dir}`"))?;
    if !uv_sync_output.status.success() {
        let code = uv_sync_output
            .status
            .code()
            .map(|code| code.to_string())
            .unwrap_or_else(|| "UNKNOWN".to_string());
        let stderr = bstr::BStr::new(&uv_sync_output.stderr);
        anyhow::bail!("`uv sync` failed to run with exit code `{code}`, stderr: {stderr}")
    }

    let system = OsSystem::new(&project_dir);
    let mut project_metadata = ProjectMetadata::discover(&project_dir, &system)?;
    // Explicitly point ty to the .venv to avoid any set VIRTUAL_ENV variable to take precedence.
    project_metadata.set_override_options(Options {
        environment: Some(EnvironmentOptions {
            python: Some(RelativePathBuf::cli(".venv")),
            ..EnvironmentOptions::default()
        }),
        ..Options::default()
    });
    let db = ProjectDatabase::fallible(project_metadata, system)?;

    let start = std::time::Instant::now();
    let mut completions = get_completions(&db, &args.file, offset)?;
    let elapsed = std::time::Instant::now().duration_since(start);
    eprintln!("total elapsed for initial completions request: {elapsed:?}");

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