What causes "Invalid enum value: {value!r} for {field_name}" in reflex-dev/reflex?

Use an exact enum value string (check the enum definition referenced by the field)

reflex-dev/reflex · error · EnvironmentVarValueError

Invalid enum value: {value!r} for {field_name}

Error message

Invalid enum value: {value!r} for {field_name}

What it means

interpret_enum_env constructs the enum type from the raw string via field_type(value); if the string isn't a valid member value, the ValueError is re-raised as EnvironmentVarValueError naming the field. Matching is on enum values, not names (unless the enum aliases them).

Source

Thrown at packages/reflex-base/src/reflex_base/environment.py:262

def interpret_enum_env(value: str, field_type: GenericType, field_name: str) -> Any:
    """Interpret an enum environment variable value.

    Args:
        value: The environment variable value.
        field_type: The field type.
        field_name: The field name.

    Returns:
        The interpreted value.

    Raises:
        EnvironmentVarValueError: If the value is invalid.
    """
    try:
        return field_type(value)
    except ValueError as ve:
        msg = f"Invalid enum value: {value!r} for {field_name}"
        raise EnvironmentVarValueError(msg) from ve


@dataclasses.dataclass(frozen=True, kw_only=True, slots=True)
class SequenceOptions:
    """Options for interpreting Sequence environment variables."""

    delimiter: str = ":"
    strip: bool = False


DEFAULT_SEQUENCE_OPTIONS = SequenceOptions()


def interpret_env_var_value(
    value: str, field_type: GenericType, field_name: str
) -> Any:
    """Interpret an environment variable value based on the field type.

View on GitHub (pinned to 45b8ed5ab7)

Solutions

Use an exact enum value string (check the enum definition referenced by the field)
If you intended the member name, use the value that member maps to
Pin/verify against the Reflex version's enum members

Example fix

# before
LOG_FORMAT=PRETTY  # enum values are 'json','text'
# after
LOG_FORMAT=text

Defensive patterns

Strategy: validation

Validate before calling

allowed = {m.value for m in MyEnum}
assert raw in allowed, f"must be one of {sorted(allowed)}"

Type guard

def is_valid_enum_value(v: str, enum_cls: type[enum.Enum]) -> bool:
    return v in {m.value for m in enum_cls}

Try / catch

except EnvironmentVarValueError:
    value = MyEnum.DEFAULT  # fallback member

Prevention

Keep an env var cheat-sheet mapping each var to its allowed enum values
Prefer enum values that match common usage to reduce mismatch

When it happens

Trigger: Setting an enum-typed env var to a string that is not one of the enum's member values, e.g. LOG_FORMAT=pretty when members are 'json' | 'text'.

Common situations: Using an enum member name instead of its value, or values that differ across Reflex versions.

Related errors

AI-assisted analysis of reflex-dev/reflex@45b8ed5ab7 (2026-08-28). Data as JSON: /api/errors/5b7370ac3588b09a. Report an issue: GitHub.