sgl-project/sglang · critical · Error

This browser does not support worker image decoding

Error message

This browser does not support worker image decoding

What it means

Thrown at worker startup when neither createImageBitmap nor ImageDecoder is available in the browser context, so JPEG/PNG frame payloads cannot be decoded off the main thread. The user should switch to a browser with WebCodecs/ImageDecoder support or a fallback decode path.

Solutions

1. Use TP in {2,4,6,8} for deterministic inference on ROCm
2. Disable the deterministic custom kernel or fall back to RCCL for unsupported sizes
3. Check visible-device masks so world size lands on a supported value

assert fa.world_size_ in (2,4,6,8), 'deterministic allreduce needs TP in (2,4,6,8)'

When it happens

Trigger: Invoking deterministic allreduce with a CustomAllreduce object whose world_size_ is not 2,4,6,8, with float32 tensors.

Common situations: Odd or >8 GPU deterministic runs (e.g. --enable-deterministic-inference with TP=3 or TP=16); deterministic mode enabled on topologies the kernel does not support.

Related errors

• Error: --model-type requires a non-empty value.
• Generate subcommand is not yet supported for model
• Previous frame size does not match current delta payload
• delta payload size mismatch: expected
• Error: --model-type requires a value.

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/5968e7d279b310c8. Report an issue: GitHub.

Appendix: source

Thrown at python/sglang/multimodal_gen/apps/realtime_webui/decoder_worker.js:102

  const bytes = payload instanceof Uint8Array ? payload : new Uint8Array(payload);
  const lengths = Array.isArray(header.payload_lengths) && header.payload_lengths.length
    ? header.payload_lengths.map(Number)
    : [bytes.byteLength];
  const payloads = [];
  let offset = 0;
  for (const length of lengths) {
    payloads.push(bytes.buffer.slice(
      bytes.byteOffset + offset,
      bytes.byteOffset + offset + length,
    ));
    offset += length;
  }
  return payloads;
}

async function encodedFramesToImageBitmaps(header, payload) {
  if (typeof createImageBitmap === "undefined") {
    throw new Error("This browser does not support worker image decoding");
  }

  const frames = await Promise.all(splitEncodedPayload(header, payload).map((framePayload) => (
    createImageBitmap(new Blob([framePayload], { type: header.content_type }))
  )));
  return {
    width: frames[0]?.width || 0,
    height: frames[0]?.height || 0,
    frame_type: "bitmap",
    frames,
  };
}

async function decode(header, payload) {
  let rawPayload;
  if (
    header.content_type === WEBP_FRAME_CONTENT_TYPE ||
    header.content_type === JPEG_FRAME_CONTENT_TYPE

View on GitHub (pinned to 0132848349)