sgl-project/sglang · error · ValueError

conditions[{index}].frame_index must be -1 or in [0, {frame_

Error message

conditions[{index}].frame_index must be -1 or in [0, {frame_count}) after 17n+5 frame alignment, got {semantic_frame_index}

What it means

The semantic frame_index must be -1 (last frame) or a non-negative int strictly below shape['frame_count'] (computed after 17n+5 frame alignment). Anything else raises this ValueError with the offending value.

Source

Thrown at python/sglang/multimodal_gen/runtime/pipelines_core/stages/model_specific_stages/minimax_h3/resolved_plan.py:343

    keyframe_pixel_indices: list[int] = []
    seen_keyframe_pixel_indices: dict[int, int] = {}
    for index, cond in enumerate(canonical["conditions"]):
        rule = profile.rule_for(
            role=str(cond["role"]), condition_type=str(cond["type"])
        )
        frame_index = cond.get("frame_index")
        resolved_frame_index = None
        if rule.requires_frame_index:
            if frame_index is None:
                raise ValueError(f"conditions[{index}].frame_index is required")
            semantic_frame_index = int(frame_index)
            frame_count = int(shape["frame_count"])
            if semantic_frame_index == -1:
                resolved_frame_index = frame_count - 1
            elif 0 <= semantic_frame_index < frame_count:
                resolved_frame_index = semantic_frame_index
            else:
                raise ValueError(
                    f"conditions[{index}].frame_index must be -1 or in "
                    f"[0, {frame_count}) after 17n+5 frame alignment, got "
                    f"{semantic_frame_index}"
                )
            previous = seen_keyframe_pixel_indices.get(resolved_frame_index)
            if previous is not None:
                raise ValueError(
                    f"conditions[{index}].frame_index resolves to "
                    f"{resolved_frame_index}, already bound by "
                    f"conditions[{previous}]"
                )
            seen_keyframe_pixel_indices[resolved_frame_index] = index
            keyframe_semantic_indices.append(semantic_frame_index)
            keyframe_pixel_indices.append(resolved_frame_index)
        materials.append(
            MiniMaxH3MaterialPlanItem(
                condition_index=index,
                role=str(cond["role"]),

View on GitHub (pinned to 0132848349)

Solutions

1. Use -1 for the last frame instead of a computed absolute index
2. Lower the frame_index below the resolved frame_count (recompute frame_count from the request's duration/resolution under 17n+5 alignment)
3. Increase the requested video length so frame_count exceeds the index

Example fix

# before
{"frame_index": frame_count}  # off-by-one, out of range
# after
{"frame_index": -1}  # semantic last frame

assert fi == -1 or 0 <= fi < frame_count, fi

def in_frame_range(fi: int, frame_count: int) -> bool:
    return fi == -1 or 0 <= fi < frame_count

When it happens

Trigger: Passing frame_index >= frame_count (e.g. 17 for a short clip), or a negative index other than -1 such as -2.

Common situations: Requesting the last frame by passing an explicit large index instead of -1; frame_count shrinking after the 17n+5 alignment for a very short requested duration, making previously valid indices out of range.

Related errors

• H3 conditioning projection tap {tap} is outside the selected
• condition_frame_indexes={cond_indexes} exceeds the latent fr
• {cpath}.frame_index requires a resolved target duration
• {cpath}.frame_index must be -1 or in [0, {aligned_frame_coun
• {profile.task} ResolvedPlan requires one or two ordered imag

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/9a73078d38e2ac27. Report an issue: GitHub.