What causes "invalid lineno {lineno_!r}: {e}" in pytest-dev/pytest?

Set the line field to a non-negative integer or omit it (use empty string)

pytest-dev/pytest · error · UsageError

invalid lineno

Error message

invalid lineno {lineno_!r}: {e}

What it means

Raised by parse_warning_filter() when the lineno field (5th colon-separated segment) of a warning filter is not a valid non-negative integer. The field is parsed via int() and explicitly checked for negativity. The original ValueError message is included.

Solutions

Set the line field to a non-negative integer or omit it (use empty string)
If you don't need a line filter, leave the field blank: "ignore::DeprecationWarning:mymodule:"
Double-check the field is a plain integer string with no decimal point or sign

Example fix

# pyproject.toml — before
filterwarnings = ["ignore::DeprecationWarning:mymodule:abc"]

# after
filterwarnings = ["ignore::DeprecationWarning:mymodule:42"]

Defensive patterns

Strategy: validation

Validate before calling

def validate_warning_filter_lineno(arg: str) -> bool:
    parts = arg.split(':')
    if len(parts) < 5 or not parts[4].strip():
        return True  # line field absent/empty is valid
    try:
        return int(parts[4].strip()) >= 0
    except ValueError:
        return False

Try / catch

from pytest import UsageError
try:
    parse_warning_filter(arg, escape=True)
except UsageError as e:
    print(f"Invalid lineno in filter: {e}")

Prevention

Use a non-negative integer or empty string for the line field
Omit the line field entirely if line filtering is not needed
Avoid floats or expressions in the line field

When it happens

Trigger: Providing a warning filter where the line field is a non-numeric string, a float, or a negative number. Example: filterwarnings = ["ignore::DeprecationWarning:mymodule:abc"] or ["ignore::DeprecationWarning:mymodule:-5"]. The int(lineno_) call raises ValueError or the negativity check fails.

Common situations: Typo in the line number field. Using a float or expression. Copying a filter with an invalid line segment. Forgetting that the line field is 1-indexed and must be non-negative.

Related errors

AI-assisted analysis of pytest-dev/pytest@0d6fbdeffa (2026-08-11). Data as JSON: /api/errors/9e44a12994b0427d. Report an issue: GitHub.

Appendix: source

Thrown at src/_pytest/config/__init__.py:2311

    try:
        category: type[Warning] = _resolve_warning_category(category_)
    except ImportError:
        raise
    except Exception:
        exc_info = ExceptionInfo.from_current()
        exception_text = exc_info.getrepr(style="native")
        raise UsageError(error_template.format(error=exception_text)) from None
    if message and escape:
        message = re.escape(message)
    if module and escape:
        module = re.escape(module) + r"\Z"
    if lineno_:
        try:
            lineno = int(lineno_)
            if lineno < 0:
                raise ValueError("number is negative")
        except ValueError as e:
            raise UsageError(
                error_template.format(error=f"invalid lineno {lineno_!r}: {e}")
            ) from None
    else:
        lineno = 0
    try:
        re.compile(message)
        re.compile(module)
    except re.error as e:
        raise UsageError(
            error_template.format(error=f"Invalid regex {e.pattern!r}: {e}")
        ) from None
    return action, message, category, module, lineno


def _resolve_warning_category(category: str) -> type[Warning]:
    """
    Copied from warnings._getcategory, but changed so it lets exceptions (specially ImportErrors)
    propagate so we can get access to their tracebacks (#9218).

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