BoundaryML/baml · error

usage: baml toolchain uninstall <version>

Error message

usage: baml toolchain uninstall <version>

What it means

Usage guard in the baml wrapper's toolchain dispatch: `baml toolchain uninstall` was invoked without a version argument. The uninstall subcommand expects exactly one operand (the toolchain version to remove) and the argument parser rejects anything with fewer or more before attempting removal.

Source

Thrown at baml_language/crates/baml/src/main.rs:389

            })?;
            if args.len() > 2 {
                return Err(anyhow!(
                    "usage: baml toolchain pin <canary|nightly|version|path>\nunexpected arguments: {}",
                    args[2..].join(" ")
                ));
            }
            pin_toolchain(selector, manifest_base_url.as_deref())
        }
        Some("update") => update_toolchain(manifest_base_url.as_deref()),
        Some("status") => status_toolchain(manifest_base_url.as_deref()),
        Some("list") => {
            list_toolchains();
            Ok(())
        }
        Some("uninstall") => {
            let version = args
                .get(1)
                .ok_or_else(|| anyhow!("usage: baml toolchain uninstall <version>"))?;
            uninstall_toolchain(version)
        }
        Some(other) => Err(anyhow!(
            "unknown toolchain command {other:?}\n\n{TOOLCHAIN_HELP}"
        )),
    }
}

fn is_help_arg(arg: &str) -> bool {
    matches!(arg, "--help" | "-h" | "help")
}

fn parse_manifest_base_url(mut args: Vec<String>) -> Result<(Vec<String>, Option<String>)> {
    let mut manifest_base_url = None;
    let mut i = 0;
    while i < args.len() {
        if args[i] == "--manifest-base-url" {
            let value = args

View on GitHub (pinned to bd85ce9dee)

Solutions

  1. Pass a version: `baml toolchain uninstall <version>` (e.g. `baml toolchain uninstall 0.210.0`).
  2. Run `baml toolchain list` to see exact version strings that can be uninstalled.
  3. Uninstall the active toolchain only if you have another one to switch to.

Example fix

# before
baml toolchain uninstall

# after
baml toolchain uninstall 0.210.0
Defensive patterns

Strategy: validation

Validate before calling

version="${VERSION:?usage: baml toolchain uninstall <version>}"
installed=$(baml toolchain list | grep -F "$version") || { echo "version not installed" >&2; exit 1; }
baml toolchain uninstall "$version"

Type guard

const hasVersionArg = (args: string[]): args is [string, string] =>
  args.length >= 2 && args[1].length > 0;

Try / catch

try:
    subprocess.run(["baml", "toolchain", "uninstall", version], check=True)
except subprocess.CalledProcessError as e:
    if "usage: baml toolchain uninstall" in e.stderr.decode():
        raise SystemExit("Uninstall requires an explicit <version> argument")

Prevention

When it happens

Trigger: Running `baml toolchain uninstall` with no version argument.

Common situations: Users assuming uninstall prompts for or removes all toolchains, scripts with empty version variables, or forgetting the exact installed version string.

Understand the failure class

Background: "no subcommand specified" and "... is required": CLI errors when a required argument is missing — this error's family across 13 libraries.

Related errors

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/f7218b332216ec21. Report an issue: GitHub.