grafana/k6 · error

got error while trying to export ArrayBufferView to bytes: %

Error message

got error while trying to export ArrayBufferView to bytes: %w

What it means

Wrap of a Sobek export failure in send(): the argument passed the ArrayBuffer.isView check, but converting the typed-array view (Uint8Array, DataView, etc.) into Go []byte via rt.ExportTo failed. This indicates the value's internal structure is not a valid view over an ArrayBuffer at export time — usually the buffer was detached or a non-standard object tricked the isView check.

Source

Thrown at internal/js/modules/k6/websockets/websockets.go:691

			data:  b,
			t:     time.Now(),
		}
	default:
		rt := w.vu.Runtime()
		isView, err := isArrayBufferView(rt, msg)
		if err != nil {
			common.Throw(rt,
				fmt.Errorf("got error while trying to check if argument is ArrayBufferView: %w", err))
		}
		if !isView {
			common.Throw(rt, fmt.Errorf("unsupported send type %T", o))
		}

		var b []byte
		err = rt.ExportTo(msg, &b)
		if err != nil {
			common.Throw(rt,
				fmt.Errorf("got error while trying to export ArrayBufferView to bytes: %w", err))
		}
		w.bufferedAmount += len(b)
		w.writeQueueCh <- message{
			mtype: websocket.BinaryMessage,
			data:  b,
			t:     time.Now(),
		}
	}
}

func (w *webSocket) sendArrayBuffer(o sobek.ArrayBuffer) {
	b := o.Bytes()
	w.bufferedAmount += len(b)
	w.writeQueueCh <- message{
		mtype: websocket.BinaryMessage,
		data:  b,
		t:     time.Now(),
	}

View on GitHub (pinned to 165bb3c1a4)

Solutions

1. Send a copy of the data instead of a view over a detached/transferred buffer
2. Construct a fresh Uint8Array from the data before sending
3. Fall back to sending a string or Blob if the view keeps failing to export

When it happens

Trigger: Thrown at internal/js/modules/k6/websockets/websockets.go:666 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@165bb3c1a4 (2026-08-18). Data as JSON: /api/errors/0534a1f226e5e60a. Report an issue: GitHub.