grafana/k6 · error

unknown WebSocket's option %s

Error message

unknown WebSocket's option %s

What it means

Returned by buildParams when the WebSocket options object contains a key that is none of headers, tags, jar or compression. The params parser is strict — unknown keys are rejected rather than ignored — so leftover or misspelled options (e.g. 'header' instead of 'headers') abort connection setup with the offending key name in the message.

Source

Thrown at internal/js/modules/k6/websockets/params.go:82

				continue
			}
			if v, ok := jarV.Export().(*httpModule.CookieJar); ok {
				parsed.cookieJar = v.Jar
			}
		case "compression":
			// deflate compression algorithm is supported - as defined in RFC7692
			// compression here relies on the implementation in gorilla/websocket package, usage is
			// experimental and may result in decreased performance. package supports
			// only "no context takeover" scenario

			algoString := strings.TrimSpace(params.Get(k).ToString().String())
			if algoString != "deflate" {
				return nil, fmt.Errorf("unsupported compression algorithm '%s', supported algorithm is 'deflate'", algoString)
			}

			parsed.enableCompression = true
		default:
			return nil, fmt.Errorf("unknown WebSocket's option %s", k)
		}
	}

	return parsed, nil
}

View on GitHub (pinned to 01ffac6f24)

Solutions

1. Remove unrecognized keys from the params object
2. Check spelling of supported keys: headers, tags, jar, compression

When it happens

Trigger: Thrown at internal/js/modules/k6/websockets/params.go:82 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@01ffac6f24 (2026-08-18). Data as JSON: /api/errors/bd84f1041260b3ef. Report an issue: GitHub.