SeleniumHQ/selenium · error · ValueError

Strategy can only be one of the following: normal, eager, no

Error message

Strategy can only be one of the following: normal, eager, none

What it means

The page_load_strategy property on an Options object validates that the value is one of the three W3C-defined strategies: 'normal', 'eager', or 'none'. Any other value raises ValueError. This maps to the W3C pageLoadStrategy capability.

Source

Thrown at py/selenium/webdriver/common/options.py:86

    See:
      - https://w3c.github.io/webdriver/#dfn-table-of-page-load-strategies.

    Args:
        strategy: the strategy corresponding to a document readiness state
    """

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

    def __get__(self, obj, cls):
        return obj._caps.get(self.name)

    def __set__(self, obj, value):
        if value in ("normal", "eager", "none"):
            obj.set_capability(self.name, value)
        else:
            raise ValueError("Strategy can only be one of the following: normal, eager, none")


class _UnHandledPromptBehaviorDescriptor:
    """How the driver should respond when an alert is present and the command sent is not handling the alert.

    See:
      - https://w3c.github.io/webdriver/#dfn-table-of-page-load-strategies:

    Args:
        behavior: behavior to use when an alert is encountered

    Returns:
        Values for implicit timeout, pageLoad timeout and script timeout if set (in milliseconds)
    """

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

View on GitHub (pinned to aa36b38e69)

Solutions

Use one of the literal lowercase strings: 'normal', 'eager', or 'none'.
Use the PageLoadStrategy enum: options.page_load_strategy = PageLoadStrategy.eager.value.
Double-check casing — values must be lowercase.

Example fix

# before
options.page_load_strategy = 'networkidle'  # raises ValueError

# after
options.page_load_strategy = 'none'
# or via enum
from selenium.webdriver.common.options import PageLoadStrategy
options.page_load_strategy = PageLoadStrategy.eager.value

Defensive patterns

Strategy: validation

Validate before calling

from selenium.webdriver.common.options import PageLoadStrategy
valid = {s.value for s in PageLoadStrategy}
if strategy not in valid:
    raise ValueError(f'Invalid page_load_strategy {strategy!r}; choose from {sorted(valid)}')
options.page_load_strategy = strategy

Type guard

from selenium.webdriver.common.options import PageLoadStrategy
def is_valid_page_load_strategy(v: str) -> bool:
    return v in {s.value for s in PageLoadStrategy}

Try / catch

try:
    options.page_load_strategy = strategy
except ValueError:
    options.page_load_strategy = 'normal'  # safe default

Prevention

Source the value from the PageLoadStrategy enum rather than a literal.
Lowercase and validate external input before assigning.

When it happens

Trigger: Setting options.page_load_strategy = 'fast', options.page_load_strategy = 'complete', or any string outside the allowed set. Case typos like 'Normal' or 'EAGER' also trigger it (comparison is case-sensitive, lowercase only).

Common situations: Confusing Selenium page-load strategies with browser/Playwright concepts ('domcontentloaded', 'load', 'networkidle'). Passing an enum or capitalized value. Copying config from a non-Selenium framework.

Related errors

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/dc91ac9abbbfae6f. Report an issue: GitHub.