sgl-project/sglang · error · ValueError

Invalid value: {other}

Error message

Invalid value: {other}

What it means

Raised by the batch-state __iadd__ (broadcasting a value across forked states) when `other` is not a single appendable value, a list, or a tuple. The multi-state container only supports appending one value to all states or element-wise lists/tuples of the same length.

Source

Thrown at python/sglang/lang/interpreter.py:1096

    def __getitem__(self, i: int):
        return self.states[i]

    def __setitem__(self, i: int, value):
        assert self.states[i] == value

    def __iadd__(self, other):
        if isinstance(other, Callable):
            # lambda function
            for i in range(len(self.states)):
                self.states[i] += other(i)
        elif isinstance(other, SglExpr):
            for i in range(len(self.states)):
                self.states[i] += other
        elif isinstance(other, (list, tuple)):
            for i in range(len(self.states)):
                self.states[i] += other[i]
        else:
            raise ValueError(f"Invalid value: {other}")

        return self

View on GitHub (pinned to 0132848349)

Solutions

1. Materialize per-state values as a list with exactly len(states) entries: states += [v1, v2, ...]
2. Or append a single str/Sgl primitive to broadcast to all states
3. Check len(your_list) == number of forked states before +=

Example fix

# before
states += (f"prompt {i}" for i in range(n))  # generator -> raises
# after
states += [f"prompt {i}" for i in range(n)]   # list, len == n_states

if isinstance(other, (list, tuple)):
    assert len(other) == len(states), f"need {len(states)} values, got {len(other)}"
    states += list(other)
else:
    states += other  # broadcast single primitive

def broadcastable(other, n_states: int) -> bool:
    if isinstance(other, (list, tuple)):
        return len(other) == n_states
    return isinstance(other, (str,)) or type(other).__name__.startswith("Sgl")

try:
    states += other
except ValueError as e:
    if "Invalid value" in str(e):
        states += list(other)  # materialize iterables
    else:
        raise

When it happens

Trigger: `states += x` where x is a dict, generator, set, or a list whose length != number of forked states; passing a tuple of the wrong arity.

Common situations: Broadcasting per-branch prompts built as a dict comprehension or generator; length mismatch after changing fork(size=N); assuming any iterable works when only list/tuple are accepted.

Related errors

• Unknown type: {type(other)}
• Tried to append None to state.
• Invalid join mode: {mode}
• spt must be a bool when provided
• Unsupported image type: {type(image)}

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/876f9f98250b4927. Report an issue: GitHub.