google/python-fire · error · InvalidEnumValue

Invalid enum value: for enum type: Operating System. Valid…

Error message

Invalid enum value: {0} for enum type: Operating System. Valid values: [{1}].

What it means

OperatingSystem.FromId maps a short OS id (e.g. 'LINUX', 'WINDOWS') to an OperatingSystem enum member. If no member's id matches the supplied os_id and error_on_unknown is true, it raises InvalidEnumValue listing the valid ids. If os_id is falsy it returns None instead of raising.

Solutions

1. Print the valid ids (the error lists them) and use one of those exact strings.
2. Map your platform string to a known id before calling (e.g. 'Darwin' -> 'MACOSX' depending on the library's id set).
3. Use OperatingSystem.Current() instead of manual id construction.
4. Pass error_on_unknown=False if a None result is acceptable.

Example fix

// before
os_enum = OperatingSystem.FromId(platform.system(), error_on_unknown=True)  # 'Darwin'
// after
os_enum = OperatingSystem.Current()

valid_ids = [v.id for v in OperatingSystem._ALL]
if os_id and os_id not in valid_ids:
    raise SystemExit(f'{os_id!r} not in {valid_ids}')

def is_known_os_id(os_id: str) -> bool:
    return os_id in {v.id for v in OperatingSystem._ALL}

try:
    os_enum = OperatingSystem.FromId(os_id, error_on_unknown=True)
except InvalidEnumValue as e:
    print(f'Unknown OS id {os_id}; valid: {e}'); sys.exit(2)

When it happens

Trigger: Calling OperatingSystem.FromId('mac', error_on_unknown=True) or FromId(platform.system()) with a raw string that is not one of the library's recognized ids; usually caused by feeding unnormalized platform strings into the enum lookup.

Common situations: Deriving the OS from platform.system() ('Darwin' vs expected ids), user-supplied config values, or a library version where the id set changed.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

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AI-assisted analysis of google/python-fire@716bbc23d7 (2026-08-28). Data as JSON: /api/errors/bd8a96a46ecc51dc. Report an issue: GitHub.

Appendix: source

Thrown at fire/console/platforms.py:136

    Args:
      os_id: str, The operating system id to parse
      error_on_unknown: bool, True to raise an exception if the id is unknown,
        False to just return None.

    Raises:
      InvalidEnumValue: If the given value cannot be parsed.

    Returns:
      OperatingSystemTuple, One of the OperatingSystem constants or None if the
      input is None.
    """
    if not os_id:
      return None
    for operating_system in OperatingSystem._ALL:
      if operating_system.id == os_id:
        return operating_system
    if error_on_unknown:
      raise InvalidEnumValue(os_id, 'Operating System',
                             [value.id for value in OperatingSystem._ALL])
    return None

  @staticmethod
  def Current():
    """Determines the current operating system.

    Returns:
      OperatingSystemTuple, One of the OperatingSystem constants or None if it
      cannot be determined.
    """
    if os.name == 'nt':
      return OperatingSystem.WINDOWS
    elif 'linux' in sys.platform:
      return OperatingSystem.LINUX
    elif 'darwin' in sys.platform:
      return OperatingSystem.MACOSX
    elif 'cygwin' in sys.platform:

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