AlexxIT/go2rtc · error

hass: no entity_id

Error message

hass: no entity_id

What it means

NewClient parses a URL and requires an entity_id query parameter identifying the Home Assistant entity to control. If the query string does not contain a non-empty entity_id, construction is aborted with this error before any network connection is attempted.

Solutions

1. Add the entity_id query parameter to the URL, e.g. ws://host:8123/api/websocket?token=TOKEN&entity_id=camera.front
2. Verify the parameter name is exactly entity_id (case-sensitive, via query.Get)
3. Log/print the parsed URL query in your config assembly to confirm the value reaches NewClient
4. Check that config templating/env expansion is not producing an empty entity_id value

Example fix

// before
client, err := hass.NewClient("ws://ha.local:8123/api/websocket?token=" + token)
// after
client, err := hass.NewClient("ws://ha.local:8123/api/websocket?token=" + token + "&entity_id=camera.front")

u, _ := url.Parse(rawURL)
if u == nil || u.Query().Get("entity_id") == "" {
    return errors.New("URL must include entity_id query parameter")
}
client, err := hass.NewClient(rawURL)

func hasEntityID(rawURL string) bool {
    u, err := url.Parse(rawURL)
    return err == nil && u.Query().Get("entity_id") != ""
}

When it happens

Trigger: Calling hass.NewClient with a URL like ws://host:8123/api/websocket?token=... but omitting &entity_id=<entity>, or misspelling the parameter (e.g. entityid=), or passing an empty entity_id value.

Common situations: Config file or environment variable building the Home Assistant URL lost the entity_id part; users copy a token-only URL from HA docs; URL building code forgets to url-encode/append the entity query param.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• hass: no token
• unsupported url:
• hass: wrong type:
• hass: wrong response
• producer without tracks

AI-assisted analysis of AlexxIT/go2rtc@c245815e75 (2026-09-07). Data as JSON: /api/errors/42147e7809c7b024. Report an issue: GitHub.

Appendix: source

Thrown at pkg/hass/client.go:26

	"github.com/AlexxIT/go2rtc/pkg/webrtc"
	pion "github.com/pion/webrtc/v4"
)

type Client struct {
	conn *webrtc.Conn
}

func NewClient(rawURL string) (*Client, error) {
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, err
	}

	query := u.Query()

	entityID := query.Get("entity_id")
	if entityID == "" {
		return nil, errors.New("hass: no entity_id")
	}

	var uri, token string

	if u.Host == "supervisor" {
		uri = "ws://supervisor/core/websocket"
		token = SupervisorToken()
	} else {
		uri = "ws://" + u.Host + "/api/websocket"
		token = query.Get("token")
	}

	if token == "" {
		return nil, errors.New("hass: no token")
	}

	// 1. Check connection to Hass
	hassAPI, err := NewAPI(uri, token)

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