Getting missing 'error' handler on this Redis client even after giving error handlers

Question

I am working on to integrate redis, @socket.io/redis-adapter, socket.io and express-session. The following is the code :

// Promisify the methods so we can use async / await with redis

bluebird.promisifyAll(redis);

const redisClient = redis.createClient({ legacyMode: true });
const subClient = redisClient.duplicate({ legacyMode: true });

bluebird.promisifyAll(redisClient);
bluebird.promisifyAll(subClient);
const redisStore = new RedisStore({ client: redisClient });

// Applying Redis middleware
app.use(
  session({
    secret: process.env.SESSION_SECRET,
    // create new redis store.
    store: redisStore,
    cookie: {
      secure: !isDevEnv, // if true: only transmit cookie over https
      httpOnly: true, // if true: prevents client side JS from reading the cookie
      maxAge: 30 * 24 * 60 * 60 * 1000, // session max age in milliseconds
    },
    resave: false,
    saveUninitialized: true,
    rolling: true,
  }),
);

In the below code redisClient and subClient are used to pass into createAdapter function . I am using redisClient in another function called IdentityCheck where we use that function to maintain single session for a user and we set the visitorId ( user id) using redis set and get function inside the function IdentityCheck

// Start the server
const server = app.listen(PORT, console.log(`App listening on port: ${PORT}`));
server.setTimeout(6 * 60 * 1000);

// Start socket io with cors enabled
const io = new Server();
io.adapter(adapter.createAdapter(redisClient, subClient));

(async () => {
  Promise.allSettled([redisClient.connect(), subClient.connect()]).then(() => {
    io.listen(server, {
      cors: {
        origin: [
          'http://localhost:3000'
        ],
      },
      transports: ['websocket'],
    });

    identityCheck.init(io, redisClient); // using redisClient in other file where we use redis get, set methods    
    redisClient.on('error', (error) => console.error('error from redisClient', error));
    subClient.on('error', (error) => console.error('error from subClient', error));
  });
})();

Even though I set the error handler as following:

redisClient.on('error', (error) => console.error('error from redisClient', error));
subClient.on('error', (error) => console.error('error from subClient', error));

I still get the missing 'error' handler on this Redis client. Am I doing anything wrong here. I am using the following versions :

{
 "express": "^4.17.1",
 "express-session": "^1.17.1",
 "redis": "4.5.1",
 "socket.io": "4.5.4",
 "socket.io-client": "4.5.4",
 "@socket.io/redis-adapter": "8.0.1",
}

redis version 4.5.1, socket.io, socket.io-client-4.5.4 and @socket.io/redis-adapter": "8.0.1",

Answer 1

I downgraded the redis version to 3.1.2 and the error has gone! I think there's something to do with redis version 4 . If anyone has correct reason please feel free to answer. thanks