SeleniumHQ/selenium · error · ValueError

Value of scale should be between 0.1 and 2

Error message

Value of scale should be between 0.1 and 2

What it means

The scale property on PrintOptions must be a number between 0.1 and 2.0 inclusive. It first validates the value is numeric (via _validate_num_property) and then checks the 0.1–2.0 range, raising ValueError if outside. This maps to the W3C print scale parameter controlling rendering zoom.

Source

Thrown at py/selenium/webdriver/common/print_page_options.py:100

    def __set__(self, obj, value) -> None:
        getattr(obj, "_validate_num_property")(f"Margin {self.name}", value)
        obj._margin[self.name] = value
        obj._print_options["margin"] = obj._margin


class _ScaleDescriptor:
    """Scale descriptor which validates scale."""

    def __init__(self, name):
        self.name = name

    def __get__(self, obj, cls) -> float | None:
        return obj._print_options.get(self.name)

    def __set__(self, obj, value) -> None:
        getattr(obj, "_validate_num_property")(self.name, value)
        if value < 0.1 or value > 2:
            raise ValueError("Value of scale should be between 0.1 and 2")
        obj._print_options[self.name] = value


class _PageOrientationDescriptor:
    """PageOrientation descriptor which validates orientation of page."""

    ORIENTATION_VALUES = ["portrait", "landscape"]

    def __init__(self, name):
        self.name = name

    def __get__(self, obj, cls) -> Orientation | None:
        return obj._print_options.get(self.name, None)

    def __set__(self, obj, value) -> None:
        if value not in self.ORIENTATION_VALUES:
            raise ValueError(f"Orientation value must be one of {self.ORIENTATION_VALUES}")
        obj._print_options[self.name] = value

View on GitHub (pinned to aa36b38e69)

Solutions

1. Set scale to a float in [0.1, 2.0], e.g. 1.0 for default, 2.0 for double size.
2. If you intended a percentage, divide by 100 (clamped to the range).

Example fix

# before
print_options.scale = 150  # out of range -> ValueError

# after
print_options.scale = 1.5

if not isinstance(scale, (int, float)) or scale < 0.1 or scale > 2:
    raise ValueError('scale must be a number in [0.1, 2.0]')
print_options.scale = scale

def is_valid_scale(v) -> bool:
    return isinstance(v, (int, float)) and 0.1 <= v <= 2.0

try:
    print_options.scale = scale
except ValueError:
    print_options.scale = 1.0  # default

When it happens

Trigger: Setting print_options.scale = 3, print_options.scale = 0, or print_options.scale = 0.05. A non-numeric value raises the earlier 'should be an integer or a float' error first.

Common situations: Assuming scale is a percentage (passing 100 instead of 1.0). Passing 0 to 'disable' scaling. Misreading the spec bounds.

Related errors

• {property_name} cannot be less than 0
• Orientation value must be one of {self.ORIENTATION_VALUES}
• Invalid page size: #{value}
• Custom page size must include :width and :height
• Unexpected compiled output format. Expected it to start with

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/61cb244583a4bd3b. Report an issue: GitHub.