redis/redis-py · error · DataError

Invalid input of type: 'bool'. Convert to a bytes, string, i

Error message

Invalid input of type: 'bool'. Convert to a bytes, string, int or float first.

What it means

Raised by Encoder.encode() when the value is a bool. bool is intentionally rejected even though it is a subclass of int, because silently encoding True as b'1' (via repr(True)='True' or int True='1') is a frequent source of subtle bugs; the library forces the caller to be explicit. DataError is a RedisError subclass (error_type=SERVER).

Source

Thrown at redis/_parsers/encoders.py:20


class Encoder:
    "Encode strings to bytes-like and decode bytes-like to strings"

    __slots__ = "encoding", "encoding_errors", "decode_responses"

    def __init__(self, encoding, encoding_errors, decode_responses):
        self.encoding = encoding
        self.encoding_errors = encoding_errors
        self.decode_responses = decode_responses

    def encode(self, value):
        "Return a bytestring or bytes-like representation of the value"
        if isinstance(value, (bytes, bytearray, memoryview)):
            return value
        elif isinstance(value, bool):
            # special case bool since it is a subclass of int
            raise DataError(
                "Invalid input of type: 'bool'. Convert to a "
                "bytes, string, int or float first."
            )
        elif isinstance(value, (int, float)):
            value = repr(value).encode()
        elif not isinstance(value, str):
            # a value we don't know how to deal with. throw an error
            typename = type(value).__name__
            raise DataError(
                f"Invalid input of type: '{typename}'. "
                f"Convert to a bytes, string, int or float first."
            )
        if isinstance(value, str):
            value = value.encode(self.encoding, self.encoding_errors)
        return value

    def decode(self, value, force=False):
        "Return a unicode string from the bytes-like representation"

View on GitHub (pinned to da03cdc7e8)

Solutions

Convert the bool to int first: r.set('flag', int(True)).
Serialize to a string the application understands: r.set('flag', 'true' if value else 'false').
Use bytes explicitly: r.set('flag', b'1' if value else b'0').
Sanitize values at the boundary: a helper that maps bool->int/str before any Redis call.

Example fix

// before
r.set("feature_x", user.has_feature)  # DataError if has_feature is bool

// after
r.set("feature_x", int(user.has_feature))

Defensive patterns

Strategy: type-guard

Validate before calling

# Reject bool at the boundary before any Redis call
def to_redis_value(v):
    if isinstance(v, bool):
        raise TypeError("bool not supported; convert with int(value)")
    return v
r.set("k", to_redis_value(flag))

Type guard

def is_redis_scalar(v) -> bool:
    return isinstance(v, (bytes, bytearray, memoryview, int, float, str)) and not isinstance(v, bool)

Try / catch

try:
    r.set("flag", value)
except redis.exceptions.DataError as e:
    if "Invalid input of type: 'bool'" in str(e):
        r.set("flag", int(value))

Prevention

Convert booleans explicitly with int() at the call site.
Add a serialization layer (Pydantic, dataclass-to-primitive) that never emits bool to Redis.
Unit-test command helpers with bool inputs to catch this before deploy.
Remember bool is a subclass of int - guard explicitly, isinstance(x, int) alone is not enough.

When it happens

Trigger: Passing a Python bool as a value or argument to any command: r.set('flag', True), r.setex('k', 60, False), r.hset('h', 'field', True), pipeline.set('k', some_bool). The encoder is hit when the command is encoded for the wire.

Common situations: Storing feature flags or boolean state directly; passing the result of a comparison (a == b) as a value; deserializing JSON booleans and forwarding them to Redis without conversion.

Related errors

AI-assisted analysis of redis/redis-py@da03cdc7e8 (2026-08-04). Data as JSON: /data/errors/b160a9b03fba202a.json. Report an issue: GitHub.