sgl-project/sglang · error · ValueError

{path} must be a non-empty string

Error message

{path} must be a non-empty string

What it means

The canonical-request validator requires certain string fields (identified by the JSON path in the message) to be non-empty strings. _require_str rejects None, non-str types, and empty strings.

Source

Thrown at python/sglang/multimodal_gen/runtime/pipelines_core/stages/model_specific_stages/minimax_h3/request_validation.py:48

    MINIMAX_H3_TASK_T2VA,
    MiniMaxH3TaskProfile,
    canonical_minimax_h3_task,
    minimax_h3_task_profile,
)
from sglang.multimodal_gen.runtime.pipelines_core.stages.model_specific_stages.minimax_h3.time_request import (
    minimax_h3_align_frame_count,
)

MINIMAX_H3_REQUEST_SCHEMA = "minimax_h3.request/v1"
MINIMAX_H3_MAX_SIGNED_SEED = (1 << 63) - 1
_ALLOWED_CONDITION_KEYS = frozenset(
    {"type", "uri", "role", "frame_index", "start_time_seconds"}
)


def _require_str(value: Any, path: str) -> str:
    if not isinstance(value, str) or value == "":
        raise ValueError(f"{path} must be a non-empty string")
    return value


def _require_int(value: Any, path: str) -> int:
    if isinstance(value, bool) or not isinstance(value, int):
        raise ValueError(f"{path} must be an integer")
    return value


def _optional_positive_finite_float(value: Any, path: str) -> float | None:
    if value is None:
        return None
    if isinstance(value, bool) or not isinstance(value, (int, float)):
        raise ValueError(f"{path} must be a number")
    normalized = float(value)
    if not math.isfinite(normalized) or normalized <= 0.0:
        raise ValueError(f"{path} must be a positive finite number")
    return normalized

View on GitHub (pinned to 0132848349)

Solutions

1. Find the field at the path in the message and supply a non-empty string
2. Treat these fields as required in your client schema, not nullable
3. Strip nulls before validation if your transport inserts them

Example fix

# before
{"target": {"uri": None}}
# after
{"target": {"uri": "file://video.mp4"}}

def clean(req: dict) -> dict:
    for p in ["target.uri", "target.type", "target.role"]:
        v = get_path(req, p)
        assert isinstance(v, str) and v, f"{p} must be a non-empty string"
    return req

def non_empty_str(v: Any) -> bool:
    return isinstance(v, str) and v != ""

When it happens

Trigger: Calling minimax_h3_validate_canonical_request (or _validate_target/_validate_conditions) with e.g. target.uri = None, type = 3, or role = "" — the message names the exact path.

Common situations: Partial request payloads, optional fields serialized as null by a JSON client, or fields dropped then defaulted to None upstream.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• {path} is required and must be an object
• MiniMax H3 request task must be a non-empty string
• MiniMax H3 requires num_inference_steps >= 2 because its vid
• quality must be one of {list(QUALITY_LEVELS)}, got {quality!
• {path} must be an integer

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/1702b02d450a053d. Report an issue: GitHub.