Supabase Realtime WebSocket fails on localhost in @supabase/supabase-js@2.49.8

[paulbland]

• I confirm this is a bug with Supabase, not my own application
• I’ve searched the Docs, GitHub Discussions, and Discord

---

🔍 Describe the Bug

In version 2.49.8 of @supabase/supabase-js, Realtime WebSocket connections fail in local development with this error:

WebSocket connection to ‘wss://<id>.supabase.co/realtime/v1/websocket?apikey=<key>&vsn=1.0.0’ failed: WebSocket is closed before the connection is established.

• ✅ The exact same code works in production
• ✅ It also works locally when using 2.49.1 or 2.49.7
• ❌ Fails consistently in local dev only when using 2.49.8 and 2.49.9

---

🧪 To Reproduce

1. Subscribe to a postgres_changes channel in local dev:

supabase
  .channel("credits-updates")
  .on("postgres_changes", { event: "UPDATE", schema: "public", table: "user_profiles" }, () => {})
  .subscribe();

2. Load the page in http://localhost:5173 (Vite + React app)
3. Observe the error in console

✅ Expected Behavior

The WebSocket connection should succeed and subscribe to the channel, just as it does in:
• Production environment
• Local dev using versions before 2.49.8

🖥️ System Info
• OS: macOS Sequoia 15.5
• Browser: Chrome 137
• Node.js: 22.14.0
• Package: @supabase/supabase-js@2.49.8
• Framework: Vite + React
• Frontend served over: http://localhost:5173

💬 Additional Context

Downgrading to @supabase/supabase-js@2.49.1 or 2.49.7 fixes the issue.
The problem appears isolated to local dev environments using Vite, but the backend setup and keys are correct.

[crivera]

same happening in 2.50

[geoguide]

Same. Fails in production too. I've been going crazy trying to figure it out.

Update: i downgraded to 2.49.7 and it works again

FWIW when i looked at my realtime logs it said my token expired 20 days ago so i think the supabase browser client is calculating the expiration wrong?

[DeLabsI0]

  async function connectToSupabase() {
    try {
      console.log('🚀 Connecting to Supabase...');
      updateConnectionStatus('connecting', 'Connecting...');

      // Create Supabase client
      supabase = window.supabase.createClient(SUPABASE_URL, API_KEY, {
        realtime: {
          params: {
            eventsPerSecond: 10,
          },
        },
      });

      console.log('🔐 Setting up authentication...');

      // Set session with access token
      const {data: authData, error: authError} =
        await supabase.auth.setSession({
          access_token: ACCESS_TOKEN,
          refresh_token: 'refresh-token',
        });

      if (authError) {
        console.log('⚠️ Auth error (may be ignorable):', authError.message);
        updateAuthStatus('connecting', 'Auth warning (continuing...)');
      } else {
        console.log('✅ Authentication set successfully');
        updateAuthStatus('connected', 'Authenticated');
      }

      // Check if user is logged in
      const {
        data: {user},
      } = await supabase.auth.getUser();
      if (user) {
        console.log('👤 Logged in user:', user.email);
        updateAuthStatus('connected', `Authenticated as ${user.email}`);
      } else {
        console.log('👤 No logged in user - continuing with anon');
        updateAuthStatus('connecting', 'Anonymous access');
      }

      console.log('📡 Creating subscriptions...');

      // Subscribe to all changes in public schema
      allChangesChannel = supabase
        .channel('schema-db-changes')
        .on(
          'postgres_changes',
          {
            schema: 'public',
            event: '*',
          },
          payload => {
            console.log('🎉🔄 REAL-TIME UPDATE DETECTED! 🔄🎉');
            addEvent(payload);
          }
        )
        .subscribe(status => {
          console.log('📡 All changes subscription status:', status);

          if (status === 'SUBSCRIBED') {
            updateConnectionStatus(
              'connected',
              'Connected - Listening for all changes'
            );
            connectBtn.disabled = true;
            disconnectBtn.disabled = false;
          } else if (status === 'CHANNEL_ERROR') {
            updateConnectionStatus('', 'Channel error');
          } else if (status === 'TIMED_OUT') {
            updateConnectionStatus('', 'Connection timed out');
          } else if (status === 'CLOSED') {
            updateConnectionStatus('', 'Connection closed');
          }
        });

For us RealTime works in Firefox and Safari, does not work in Chrome

From above we are getting in Chrome:
WebSocket connection to ‘wss://.supabase.co/realtime/v1/websocket?apikey=&vsn=1.0.0’ failed:

Firefox and Safari works without any issues

[hyper-lode]

I just tried updating to 2.50.1 which solved #1437 but now I'm getting these errors too in Chrome and localhost:

RealtimeClient.js:151 WebSocket connection to 'wss://{key}.supabase.co/realtime/v1/websocket?apikey={key}&vsn=1.0.0' failed:

I'm on Next.js 15.3.4

Downgrading back to 2.49.9 solves everything for me

[actraiser]

RealtimeClient.js:151 WebSocket connection to 'wss://{key}.supabase.co/realtime/v1/websocket?apikey={key}&vsn=1.0.0' failed:

Same for me, had to downgrade again - using self hosted supabase with realtime container supabase/realtime:v2.36.18 if that helps.

[Yue-plus]

2.49.9 is an available version!
2.49.9 是一个可用版本！

I'm working on an Electron app and this issue occurs with both 2.50.1 and 2.50.0.
我正在开发 Electron 应用，使用 2.50.1 和 2.50.0 均会出现此问题。

[zicovsky]

Not sure what happened but even downgrading is not working for me, for some reason. Firefox works, but Chrome simply doesn't, and I get the same error as OP. This is driving me crazy over the past few days.

[paulbland]

This appears to be fixed for me on 2.50.1