SeleniumHQ/selenium · error · ValueError

Orientation value must be one of {self.ORIENTATION_VALUES}

Error message

Orientation value must be one of {self.ORIENTATION_VALUES}

What it means

The orientation property on PrintOptions only accepts 'portrait' or 'landscape' (lowercase). Any other value raises ValueError. The allowed values are stored in ORIENTATION_VALUES and interpolated into the message.

Source

Thrown at py/selenium/webdriver/common/print_page_options.py:117

        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


class _ValidateTypeDescriptor:
    """Base Class Descriptor which validates type of any subclass attribute."""

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

    def __get__(self, obj, cls):
        return obj._print_options.get(self.name, None)

    def __set__(self, obj, value) -> None:
        if not isinstance(value, self.expected_type):
            raise ValueError(f"{self.name} should be of type {self.expected_type.__name__}")
        obj._print_options[self.name] = value

View on GitHub (pinned to aa36b38e69)

Solutions

1. Use exactly 'portrait' or 'landscape' (lowercase).
2. Lowercase external input before assigning: value.lower().

Example fix

# before
print_options.orientation = 'Portrait'  # raises ValueError

# after
print_options.orientation = 'portrait'
# or normalize
print_options.orientation = user_input.strip().lower() if user_input.strip().lower() in ('portrait','landscape') else 'portrait'

ALLOWED = {'portrait','landscape'}
value = value.strip().lower()
if value not in ALLOWED:
    raise ValueError(f'orientation must be one of {sorted(ALLOWED)}')
print_options.orientation = value

def is_valid_orientation(v: str) -> bool:
    return isinstance(v, str) and v.strip().lower() in {'portrait','landscape'}

try:
    print_options.orientation = value
except ValueError:
    print_options.orientation = 'portrait'

When it happens

Trigger: Setting print_options.orientation = 'Portrait' (capitalized), 'horizontal', 'vertical', or '0'. The check is case-sensitive lowercase.

Common situations: Capitalizing the value. Using synonyms ('vertical'/'horizontal'). Pulling orientation from an enum or external source with different naming.

Related errors

• Value of scale should be between 0.1 and 2
• {property_name} cannot be less than 0
• 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/1490924d47a2862a. Report an issue: GitHub.