denoland/deno · error · AnyError

APPDATA not set

Error message

APPDATA not set

What it means

Windows counterpart of the HOME lookup: get_user_data_dir() resolves the Jupyter user data dir to `%APPDATA%\jupyter`. If the APPDATA environment variable is unset (it is normally maintained by the user shell), Deno cannot compute the data directory and `deno jupyter install`/`uninstall`/`status` fail before writing any kernelspec.

Solutions

1. Set APPDATA before the command: `set APPDATA=%USERPROFILE%\AppData\Roaming` then re-run
2. For scheduled tasks/services, enable 'Load user profile' or set the variable explicitly in the task environment
3. In automation, point APPDATA at a known writable directory

Example fix

# before
deno jupyter install

# after (cmd)
set APPDATA=%USERPROFILE%\AppData\Roaming
deno jupyter install

if (!Deno.env.get('APPDATA')) {
  throw new Error('APPDATA is not set; set it before running deno jupyter install');
}

const hasAppdata = (): boolean => Deno.env.has('APPDATA');

When it happens

Trigger: Any `deno jupyter` subcommand needing the user data dir on Windows with APPDATA unset — scheduled tasks, services running as SYSTEM, stripped CI environments, or shells started without the standard user environment block.

Common situations: Windows Task Scheduler or service contexts where the user profile is not loaded; CI runners that clear the environment; portable/MSYS shells that do not propagate APPDATA; accounts without a roaming profile.

Understand the failure class

Background: "environment variable is not set" and "Missing keys in environment" errors: what missing required env var messages mean and how to fix them — this error's family across 28 libraries.

Related errors

• HOME not set
• Not running in GitHub Actions
• vsock is not supported on this platform
• Automatic provenance is only available in GitHub Actions
• batch file arguments are invalid

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/52e175d4c4bcbaa0. Report an issue: GitHub.

Appendix: source

Thrown at cli/tools/jupyter/install.rs:80

}

fn get_user_data_dir() -> Result<PathBuf, AnyError> {
  if let Some(env_var) = std::env::var_os(TEST_ENV_VAR_NAME) {
    return Ok(PathBuf::from(env_var));
  }
  // Platform-specific Jupyter user data directory (mirrors runtimelib behavior).
  #[cfg(target_os = "macos")]
  {
    let home = std::env::var_os("HOME")
      .map(PathBuf::from)
      .ok_or_else(|| deno_core::anyhow::anyhow!("HOME not set"))?;
    Ok(home.join("Library").join("Jupyter"))
  }
  #[cfg(target_os = "windows")]
  {
    let appdata = std::env::var_os("APPDATA")
      .map(PathBuf::from)
      .ok_or_else(|| deno_core::anyhow::anyhow!("APPDATA not set"))?;
    Ok(appdata.join("jupyter"))
  }
  #[cfg(not(any(target_os = "macos", target_os = "windows")))]
  {
    if let Some(xdg) = std::env::var_os("XDG_DATA_HOME") {
      return Ok(PathBuf::from(xdg).join("jupyter"));
    }
    let home = std::env::var_os("HOME")
      .map(PathBuf::from)
      .ok_or_else(|| deno_core::anyhow::anyhow!("HOME not set"))?;
    Ok(home.join(".local").join("share").join("jupyter"))
  }
}

pub fn status(maybe_name: Option<&str>) -> Result<(), AnyError> {
  let user_data_dir = get_user_data_dir()?;

  let kernel_name = maybe_name.unwrap_or("deno");

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