Freika/dawarich · warning

[MapChannel] Failed to subscribe to family channel:

Error message

[MapChannel] Failed to subscribe to family channel:

What it means

The map page subscribes to FamilyLocationsChannel inside a try/catch to receive live family-member locations. consumer.subscriptions.create throws synchronously when the consumer is in a bad state, the cable connection URL is wrong, or the channel identifier is malformed. When it throws, family live updates are unavailable for the session; points and tracks subscriptions still proceed.

Source

Thrown at app/javascript/maps_maplibre/channels/map_channel.js:65

          },

          disconnected() {
            console.log("FamilyLocationsChannel disconnected")
            callbacks.disconnected?.("family")
          },

          received(data) {
            console.log("FamilyLocationsChannel received:", data)
            callbacks.received?.({
              type: "family_location",
              member: data,
            })
          },
        },
      )
    }
  } catch (error) {
    console.warn("[MapChannel] Failed to subscribe to family channel:", error)
  }

  // Subscribe to points channel for real-time point updates (only if live mode is enabled)
  if (enableLiveMode) {
    try {
      subscriptions.points = consumer.subscriptions.create("PointsChannel", {
        connected() {
          console.log("PointsChannel connected")
          callbacks.connected?.("points")
        },

        disconnected() {
          console.log("PointsChannel disconnected")
          callbacks.disconnected?.("points")
        },

        received(data) {
          console.log("PointsChannel received:", data)

View on GitHub (pinned to 97fad417c5)

Solutions

1. Open /cable in the browser — it must not 404, and the WS upgrade should appear as 101 Switching Protocols in the Network tab
2. Configure the proxy to pass Connection/Upgrade headers and allow long-lived connections for the cable path
3. Ensure Rails allowed_request_origins includes the site origin and the cable URL uses wss:// when the page is https
4. After backend deploys that touch channels, cache-bust stale JS bundles

Example fix

// before
subscriptions.family = consumer.subscriptions.create("FamilyLocationsChannel", { ...handlers })
// after
if (typeof consumer?.subscriptions?.create === "function") {
  subscriptions.family = consumer.subscriptions.create("FamilyLocationsChannel", {
    rejected() { console.warn("[MapChannel] Family channel rejected subscription") },
    ...handlers,
  })
}

if (!consumer || typeof consumer.subscriptions?.create !== "function") return
const familyEl = document.querySelector("[data-family-members-features-value]")
if (!familyEl) return // family feature disabled — skip the channel entirely

/** @param {unknown} c @returns {boolean} */
function isActionCableConsumer(c) {
  return Boolean(
    c &&
    typeof c === "object" &&
    typeof c.subscriptions?.create === "function"
  )
}

try {
  subscriptions.family = consumer.subscriptions.create("FamilyLocationsChannel", {
    rejected() { console.warn("[MapChannel] Family channel rejected subscription") },
    ...handlers,
  })
} catch (error) {
  console.warn("[MapChannel] Failed to subscribe to family channel:", error)
  // Realtime family locations are an enhancement: keep the map usable without them
}

When it happens

Trigger: ActionCable mount path changed server-side so the cable URL 404s; the WebSocket to /cable failing CORS or blocked by a proxy that does not upgrade; the family features element present in the DOM but the channel identifier string not matching the Rails channel; a stale cached JS bundle calling a renamed channel.

Common situations: Reverse proxies (nginx/traefik) not passing Upgrade/Connection headers for the cable path; dev served over https while the cable URL uses ws:// (mixed content); backend channel renames during upgrades; older bundles cached by the browser or CDN.

Related errors

• [MapChannel] Failed to subscribe to tracks channel:
• [MapChannel] ActionCable consumer not available
• [MapChannel] Failed to subscribe to points channel:
• [Realtime Controller] Maps controller not found
• [Realtime Controller] Points layer not found

AI-assisted analysis of Freika/dawarich@97fad417c5 (2026-08-21). Data as JSON: /api/errors/bb66a0a08c58974d. Report an issue: GitHub.