jdx/mise · error

cannot export version pin

Error message

cannot export version pin '{spec}' = '{version}': pin nixpkgs in the importing NixOS configuration instead

What it means

The Nix export renders packages as bare `pkgs.<attribute>` entries in a NixOS module; attribute entries carry no version, so a pinned version cannot be represented. mise throws this when a `nix:` bootstrap package has a version other than `latest`, telling you to pin nixpkgs in the importing NixOS configuration instead.

Solutions

1. Change the package entry in `[bootstrap.packages]` to version `latest` before exporting.
2. Pin the nixpkgs revision (e.g. via `nixpkgs.url` / an overlay) in the importing NixOS configuration to control versions there.
3. Keep the version-pinned package managed by mise/Nix outside of the exported module rather than via bootstrap packages.

Example fix

# before (mise.toml)
[bootstrap.packages]
"nix:hello" = "1.2"

# after
[bootstrap.packages]
"nix:hello" = "latest"

// Only 'latest' versions can be exported for nix packages
const pinned = Object.entries(packages)
  .filter(([k, v]) => k.startsWith("nix:") && v !== "latest");
if (pinned.length) throw new Error(`unpin these before export: ${pinned.map(([k]) => k).join(", ")}`);

const isExportableNixEntry = ([spec, version]) =>
  spec.startsWith("nix:") && version === "latest";

When it happens

Trigger: Running `mise bootstrap packages export --format nix` while `[bootstrap.packages]` contains an entry like `"nix:hello" = "1.2"` (any non-`latest` version string).

Common situations: A user pinned a nix package version in mise.toml for reproducibility and then runs export to generate a NixOS module; the pin has no equivalent in `environment.systemPackages`.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• cannot export ' ': use a shorthand attribute such as…
• a branch name is required
• a glob is required
• a repository preview directory requires a dry run
• a repository url is required

AI-assisted analysis of jdx/mise@533346cc37 (2026-09-17). Data as JSON: /api/errors/15b13a66e8ce4ef9. Report an issue: GitHub.

Appendix: source

Thrown at src/cli/system/export.rs:61

        miseprint!("{module}")?;
        Ok(())
    }
}

fn render<'a>(packages: impl IntoIterator<Item = (&'a str, &'a str)>) -> Result<String> {
    let mut attributes = std::collections::BTreeSet::new();
    for (spec, version) in packages {
        let name = spec
            .strip_prefix("nix:")
            .ok_or_else(|| eyre::eyre!("expected a nix: package: {spec}"))?;
        let request = Installable::parse(name)?;
        if request.explicit {
            bail!(
                "cannot export '{spec}': use a shorthand attribute such as nix:ripgrep; the importing NixOS configuration owns the package source"
            );
        }
        if version != "latest" {
            bail!(
                "cannot export version pin '{spec}' = '{version}': pin nixpkgs in the importing NixOS configuration instead"
            );
        }
        attributes.insert(
            request
                .attribute
                .split('.')
                .map(nix_string)
                .collect::<Vec<_>>()
                .join("."),
        );
    }
    let mut output = String::from(
        "# Generated by mise bootstrap packages export --format nix\n{ pkgs, ... }:\n{\n  environment.systemPackages = [\n",
    );
    for attribute in attributes {
        output.push_str(&format!("    pkgs.{attribute}\n"));
    }

View on GitHub (pinned to 533346cc37)