sgl-project/sglang · error · ValueError

extra_config[{!r}] must be a boolean-like value (true/false,

Error message

extra_config[{!r}] must be a boolean-like value (true/false, 1/0, yes/no, on/off), got {!r}

What it means

Strict boolean coercion for an extra_config key failed: the value is neither bool/int nor one of the accepted strings ('true'/'false','1'/'0','yes'/'no','on'/'off' after strip/lower).

Source

Thrown at python/sglang/srt/mem_cache/storage/umbp/umbp_store.py:79

_TRUE_STRINGS = frozenset({"1", "true", "yes", "on"})
_FALSE_STRINGS = frozenset({"0", "false", "no", "off"})


def _strict_bool(value: Any, key: str) -> bool:
    """Strict boolean parse; raises rather than silently inverting (bool("false") is True)."""
    if isinstance(value, bool):
        return value
    if isinstance(value, int):
        if value in (0, 1):
            return bool(value)
    elif isinstance(value, str):
        norm = value.strip().lower()
        if norm in _TRUE_STRINGS:
            return True
        if norm in _FALSE_STRINGS:
            return False
    raise ValueError(
        f"extra_config[{key!r}] must be a boolean-like value "
        f"(true/false, 1/0, yes/no, on/off), got {value!r}"
    )


def _cast_like(current: Any, value: Any, key: str) -> Any:
    """Cast ``value`` to match the type of an existing config attribute."""
    if isinstance(current, bool):
        return _strict_bool(value, key)
    if isinstance(current, int):
        return int(value)
    if isinstance(current, float):
        return float(value)
    return str(value)


def _default_node_address() -> str:
    try:

View on GitHub (pinned to 0132848349)

Solutions

Fix the value to a boolean-like literal (true/false, 1/0, yes/no, on/off)
Validate the extra_config dict against the documented schema before constructing the store

Example fix

# before
extra = {'prefault': 'enabled'}
# after
extra = {'prefault': True}

Defensive patterns

Strategy: validation

Validate before calling

_BOOLS = {'true':True,'false':False,'1':True,'0':False,'yes':True,'no':False,'on':True,'off':False}
def valid_bool(v):
    return isinstance(v, bool) or (isinstance(v, int) and v in (0,1)) or (isinstance(v, str) and v.strip().lower() in _BOOLS)
assert all(valid_bool(v) for k, v in extra.items() if k in BOOL_KEYS)

Type guard

def is_boolean_like(v) -> bool:
    _B={'true','false','1','0','yes','no','on','off'}
    return isinstance(v,bool) or (isinstance(v,int) and v in (0,1)) or (isinstance(v,str) and v.strip().lower() in _B)

Prevention

Use real JSON booleans in extra_config, not strings
Validate extra_config with a schema before launching the server

When it happens

Trigger: Passing extra_config={'prefault': 'maybe'} or another non-boolean-like value to the UMBP store constructor; _cast_like routes it into _strict_bool which raises ValueError naming the key.

Common situations: Typos in server CLI --storage-extra-config JSON, quoting issues making the value a nested list/dict, or copy-pasted config from a different schema.

Understand the failure class

Background: Config validation failed: what "invalid value for {key}" and settings-rejection errors mean across 19 open-source libraries — this error's family across 19 libraries.

Related errors

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/5d843191027452c3. Report an issue: GitHub.