pytest-dev/pytest · error · ValueError

unknown configuration type

Error message

unknown configuration type: {type}

What it means

Config__getini_unknown_type (legacypath.py:395) handles ini option retrieval for the legacy 'pathlist' type and raises ValueError('unknown configuration type: {type}', value) for any other unrecognized type. This path is reached when a plugin registers an ini option with a 'type' string that the core config does not know how to coerce (only 'pathlist' is handled here as a legacy shim).

Solutions

1. Use a standard type string in addini (e.g. 'string', 'bool', 'int', 'pathlist', 'args', 'linelist', 'paths').
2. If a custom type is required, post-process the raw string value yourself instead of declaring a custom type.
3. Verify the ini option's registered type against the list supported by your pytest version.

Example fix

// before
parser.addini('targets', type='csvlist', default=[])
value = config.getini('targets')
// after
parser.addini('targets', type='linelist', default=[])
value = [x.split(',') for x in config.getini('targets'))]

ALLOWED = {'string','bool','int','float','pathlist','paths','args','linelist','choice'}
def addini_checked(parser, name, type, help, **kw):
    assert type in ALLOWED, f'unsupported ini type {type!r}; use one of {ALLOWED}'
    parser.addini(name, type=type, help=help, **kw)

def is_known_ini_type(t: str) -> bool:
    return t in {'string','bool','int','float','pathlist','paths','args','linelist','choice'}

When it happens

Trigger: A plugin/conftest calling parser.addini('opt', type='mytype') where 'mytype' is not one of the recognized type names, and then code calls config.getini('opt') triggering the legacy fallback; mixing the fspath/legacypath compatibility layer with a custom type.

Common situations: Custom ini types added without registering a corresponding getini handler; pytest version mismatch where a type previously handled by legacypath no longer is; plugin conflicts overriding getini behavior.

Related errors

• help argument cannot be None for
• ' ' is not recognized as a logging level name for ' '…
• unknown configuration value
• alias conflicts with existing configuration option
• is already an alias of

AI-assisted analysis of pytest-dev/pytest@0d6fbdeffa (2026-08-11). Data as JSON: /api/errors/858d32903583257a. Report an issue: GitHub.

Appendix: source

Thrown at src/_pytest/legacypath.py:395

def Session_startdir(self: Session) -> LEGACY_PATH:
    """The path from which pytest was invoked.

    Prefer to use ``startpath`` which is a :class:`pathlib.Path`.

    :type: LEGACY_PATH
    """
    return legacy_path(self.startpath)


def Config__getini_unknown_type(self, name: str, type: str, value: str | list[str]):
    if type == "pathlist":
        # TODO: This assert is probably not valid in all cases.
        assert self.inipath is not None
        dp = self.inipath.parent
        input_values = shlex.split(value) if isinstance(value, str) else value
        return [legacy_path(str(dp / x)) for x in input_values]
    else:
        raise ValueError(f"unknown configuration type: {type}", value)


def Node_fspath(self: Node) -> LEGACY_PATH:
    """(deprecated) returns a legacy_path copy of self.path"""
    return legacy_path(self.path)


def Node_fspath_set(self: Node, value: LEGACY_PATH) -> None:
    self.path = Path(value)


@hookimpl(tryfirst=True)
def pytest_load_initial_conftests(early_config: Config) -> None:
    """Monkeypatch legacy path attributes in several classes, as early as possible."""
    mp = MonkeyPatch()
    early_config.add_cleanup(mp.undo)

    # Add Cache.makedir().

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