astral-sh/uv · error · anyhow::Error

The `--default` flag cannot be used with multiple targets

Error message

The `--default` flag cannot be used with multiple targets

What it means

Error "The `--default` flag cannot be used with multiple targets" thrown in astral-sh/uv.

Source

Thrown at crates/uv/src/commands/python/install.rs:325

    concurrency: &Concurrency,
    preview: Preview,
    printer: Printer,
) -> Result<ExitStatus> {
    let start = std::time::Instant::now();

    // TODO(zanieb): We should consider marking the Python installation as the default when
    // `--default` is used. It's not clear how this overlaps with a global Python pin, but I'd be
    // surprised if `uv python find` returned the "newest" Python version rather than the one I just
    // installed with the `--default` flag.
    if default && !preview.is_enabled(PreviewFeature::PythonInstallDefault) {
        warn_user!(
            "The `--default` option is experimental and may change without warning. Pass `--preview-features {}` to disable this warning",
            PreviewFeature::PythonInstallDefault
        );
    }

    if default && targets.len() > 1 {
        anyhow::bail!("The `--default` flag cannot be used with multiple targets");
    }

    // Read the existing installations, lock the directory for the duration
    let installations = ManagedPythonInstallations::from_settings(install_dir.clone())?.init()?;
    let installations_dir = installations.root();
    let scratch_dir = installations.scratch();
    let _lock = installations.lock().await?;
    let existing_installations: Vec<_> = installations
        .find_all()?
        .inspect(|installation| trace!("Found existing installation {}", installation.key()))
        .collect();

    // Resolve the requests
    let mut is_default_install = false;
    let mut is_unspecified_upgrade = false;
    let retry_policy = client_builder.retry_policy();
    let download_list = ManagedPythonDownloadList::new(
        &client_builder,

View on GitHub (pinned to f1a42680ff)

When it happens

Trigger: Thrown at crates/uv/src/commands/python/install.rs:325 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of astral-sh/uv@f1a42680ff (2026-08-16). Data as JSON: /api/errors/0ee0b7a0f0c97946. Report an issue: GitHub.